testsuite: Fix for gcc-4.8: gdb.base/jit.exp gdb.base/jit-so.exp

testsuite: Fix for gcc-4.8: gdb.base/jit.exp gdb.base/jit-so.exp

on CentOS-7.2 I get

Running /home/jkratoch/redhat/gdb-test-reg/gdb/testsuite/gdb.base/jit.exp ...
FAIL: gdb.base/jit.exp: one_jit_test-1: continue to breakpoint: break here 2 (the program exited)
FAIL: gdb.base/jit.exp: one_jit_test-2: continue to breakpoint: break here 2 (the program exited)
FAIL: gdb.base/jit.exp: attach: one_jit_test-2: continue to breakpoint: break here 2 (the program exited)
FAIL: gdb.base/jit.exp: attach: one_jit_test-2: break here 2: set var wait_for_gdb = 1
FAIL: gdb.base/jit.exp: attach: one_jit_test-2: break here 2: detach (the program is no longer running)
FAIL: gdb.base/jit.exp: attach: one_jit_test-2: break here 2: attach
FAIL: gdb.base/jit.exp: attach: one_jit_test-2: break here 2: set var wait_for_gdb = 0
FAIL: gdb.base/jit.exp: PIE: one_jit_test-1: continue to breakpoint: break here 2 (the program exited)
Running /home/jkratoch/redhat/gdb-test-reg/gdb/testsuite/gdb.base/jit-so.exp ...
FAIL: gdb.base/jit-so.exp: one_jit_test-1: continue to breakpoint: break here 2 (the program exited)
FAIL: gdb.base/jit-so.exp: one_jit_test-2: continue to breakpoint: break here 2 (the program exited)

since:

85af34ee0211eedf8d30a5c44dfc59dddf8b512a is the first bad commit
commit 85af34ee0211eedf8d30a5c44dfc59dddf8b512a
Author: Pedro Alves <palves@redhat.com>
Date:   Thu Mar 31 19:28:47 2016 +0100
    Add regression test for PR gdb/19858 (JIT code registration on attach)

The compiled code's .debug_line is wrong (for the simplistic approach of GDB
to put a breakpoint on the first address belonging to that source line) and so
GDB misses the breakpoint at the last line:
          WAIT_FOR_GDB; return 0;  /* gdb break here 2  */

Most of the patch is just about reindentation, no changes there.

gdb/testsuite/ChangeLog
2016-04-08  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix compatibility with gcc-4.8.5-4.el7.x86_64.
	* gdb.base/jit-main.c: Use exit after usage.