darwin, configuration, check properly for dwarf2 debug line support

darwin, configuration, check properly for dwarf2 debug line support

This corrects a long-standing misconfiguration for Darwin.
The assembler supports the “.file” and “.loc” directives, but
the GCC configury was not detecting this because it was
using objdump, which does not exist on most Darwin installations.

We added support for “otool” to GCC and now we can use that to
make the check that’s done with objdump on ELF targets.

2018-12-24  Iain Sandoe  <iain@sandoe.co.uk>

	* configure.ac (dwarf2_debug_line): Check for the debug_line
	section using otool when there’s no objdump available.
	* configure: Regenerate.

From-SVN: r267393