Garbage collecting debug sections

Garbage collecting debug sections

I noticed that _bfd_elf_gc_mark_extra_sections attempts to unmark
related debug sections when it finds an unmarked code section.
When it finds .text.foo is unmarked, for example, it removes
.debug_line.text.foo as well (using the section name as a suffix
match check.

However, it bails out after finding one such section.

bfd/
	* elflink.c (_bfd_elf_gc_mark_extra_sections): Don't break on
	first matching debug section.
ld/testsuite/
	* ld-gc/all-debug-sections.d: New file.
	* ld-gc/all-debug-sections.s: Likewise.
	* ld-gc/gc.exp: Execute new testcase.