re PR libfortran/54572 (Use libbacktrace library)

	PR libfortran/54572

	* Makefile.def: Make libgfortran depend on libbacktrace.
	* Makefile.in: Regenerate.

	* config-lang.in: Add libbacktrace to target_libs.

	* Makefile.am (libgfortran_la_LDFLAGS): Link in libbacktrace.
	(AM_CPPFLAGS): Add libbacktrace directories to include paths.
	* Makefile.in: Regenerate.
	* aclocal.m4: Regenerate.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Remove checks for strtok_r, wait, execve, pipe,
	and dup2. Remove call to GCC_CHECK_UNWIND_GETIPINFO.
	* libgfortran.h (full_exe_path, find_addr2line, backtrace): Remove
	prototypes.
	(show_backtrace): Add prototype.
	* runtime/backtrace.c: Rework file entirely.
	* runtime/compile_options.c (backtrace_handler): Rename backtrace
	to show_backtrace.
	(maybe_find_addr2line): Remove function.
	(set_options): Remove call to maybe_find_addr2line.
	* runtime/error.c (sys_abort): Rename backtrace to show_backtrace.
	* runtime/main.c (store_exe_path): Empty function body.
	(full_exe_path, gfstrtok_r, find_addr2line): Remove functions.
	(cleanup): Don't free removed variables.
	* runtime/minimal.c (full_exe_path): Remove function.
	(set_args): Don't set exe_path.

	* gfortran.dg/backtrace_1.f90: New test.

From-SVN: r227106