libdw: Add locking to dwarf_getsrcfiles, dwarf_getsrclines, dwarf_macro_getsrcfiles

libdw: Add locking to dwarf_getsrcfiles, dwarf_getsrclines, dwarf_macro_getsrcfiles

	* libdw/dwarf_begin_elf.c (dwarf_begin_elf): Init macro_lock.
	* libdw/dwarf_end.c (cu_free): Free src_lock.
	(dwarf_end): Free macro_lock.
	* libdw/dwarf_getsrcfiles.c (dwarf_getsrcfiles): Use src_lock.
	* libdw/dwarf_getsrclines.c (dwarf_getsrclines): Ditto.
	* libdw/dwarf_macro_getsrclines.c (dwarf_macro_getsrclines): Use
	macro_lock.
	* libdw/libdwP.h (struct Dwarf): Define macro_lock.
	(struct Dwarf_CU): Define src_lock.
	* libdw/libdw_findcu.c (__libdw_intern_next_unit): Init src_lock.

Signed-off-by: Aaron Merey <amerey@redhat.com>