Fix: cygwin does not honour LD_LIBRARY_PATH

Fix: cygwin does not honour LD_LIBRARY_PATH

Cygwin, just like Windows, relies on PATH to find libraries.

Error:

15:16:01 FAIL: python-plugin-provider/test_python_plugin_provider 1 - test_python_plugin_provider (unittest.loader._FailedTest)
15:16:01 # python-plugin-provider/test_python_plugin_provider: Traceback (most recent call last):
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/usr/lib/python3.6/unittest/case.py", line 59, in testPartExecutor
15:16:01 # python-plugin-provider/test_python_plugin_provider: yield
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/usr/lib/python3.6/unittest/case.py", line 605, in run
15:16:01 # python-plugin-provider/test_python_plugin_provider: testMethod()
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/usr/lib/python3.6/unittest/loader.py", line 34, in testFailure
15:16:01 # python-plugin-provider/test_python_plugin_provider: raise self._exception
15:16:01 # python-plugin-provider/test_python_plugin_provider: ImportError: Failed to import test module: test_python_plugin_provider
15:16:01 # python-plugin-provider/test_python_plugin_provider: Traceback (most recent call last):
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/cygdrive/c/Users/jenkins/workspace/babeltrace_master_winbuild/arch/cygwin/build/std/conf/std/src/babeltrace/src/bindings/python/bt2/build/build_lib/bt2/native_bt.py", line 14, in swig_import_helper
15:16:01 # python-plugin-provider/test_python_plugin_provider: return importlib.import_module(mname)
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
15:16:01 # python-plugin-provider/test_python_plugin_provider: return _bootstrap._gcd_import(name[level:], package, level)
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "<frozen importlib._bootstrap>", line 994, in _gcd_import
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "<frozen importlib._bootstrap>", line 971, in _find_and_load
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "<frozen importlib._bootstrap>", line 658, in _load_unlocked
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "<frozen importlib._bootstrap>", line 571, in module_from_spec
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "<frozen importlib._bootstrap_external>", line 922, in create_module
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
15:16:01 # python-plugin-provider/test_python_plugin_provider: ImportError: No such file or directory
15:16:01 # python-plugin-provider/test_python_plugin_provider: During handling of the above exception, another exception occurred:
15:16:01 # python-plugin-provider/test_python_plugin_provider: Traceback (most recent call last):
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/usr/lib/python3.6/unittest/loader.py", line 428, in _find_test_path
15:16:01 # python-plugin-provider/test_python_plugin_provider: module = self._get_module_from_name(name)
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/usr/lib/python3.6/unittest/loader.py", line 369, in _get_module_from_name
15:16:01 # python-plugin-provider/test_python_plugin_provider: __import__(name)
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/cygdrive/c/Users/jenkins/workspace/babeltrace_master_winbuild/arch/cygwin/build/std/conf/std/src/babeltrace/tests/python-plugin-provider/test_python_plugin_provider.py", line 20, in <module>
15:16:01 # python-plugin-provider/test_python_plugin_provider: import bt2
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/cygdrive/c/Users/jenkins/workspace/babeltrace_master_winbuild/arch/cygwin/build/std/conf/std/src/babeltrace/src/bindings/python/bt2/build/build_lib/bt2/__init__.py", line 26, in <module>
15:16:01 # python-plugin-provider/test_python_plugin_provider: from bt2.clock_class import *
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/cygdrive/c/Users/jenkins/workspace/babeltrace_master_winbuild/arch/cygwin/build/std/conf/std/src/babeltrace/src/bindings/python/bt2/build/build_lib/bt2/clock_class.py", line 23, in <module>
15:16:01 # python-plugin-provider/test_python_plugin_provider: from bt2 import native_bt, object, utils
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/cygdrive/c/Users/jenkins/workspace/babeltrace_master_winbuild/arch/cygwin/build/std/conf/std/src/babeltrace/src/bindings/python/bt2/build/build_lib/bt2/native_bt.py", line 17, in <module>
15:16:01 # python-plugin-provider/test_python_plugin_provider: _native_bt = swig_import_helper()
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/cygdrive/c/Users/jenkins/workspace/babeltrace_master_winbuild/arch/cygwin/build/std/conf/std/src/babeltrace/src/bindings/python/bt2/build/build_lib/bt2/native_bt.py", line 16, in swig_import_helper
15:16:01 # python-plugin-provider/test_python_plugin_provider: return importlib.import_module('_native_bt')
15:16:01 # python-plugin-provider/test_python_plugin_provider: File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
15:16:01 # python-plugin-provider/test_python_plugin_provider: return _bootstrap._gcd_import(name[level:], package, level)
15:16:01 # python-plugin-provider/test_python_plugin_provider: ModuleNotFoundError: No module named '_native_bt'

Change-Id: Ife8ce952a9dc34a78f3ee293e52a13c7f8a1310d
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1694
Reviewed-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Tested-by: jenkins <jenkins@lttng.org>