Log environment variables in set_ld_library_path_env_vars

GNU linker sets DT_RPATH from the environment variable LD_RUN_PATH.
set_ld_library_path_env_vars sets a few environment variables including
LD_RUN_PATH.  This patch logs all environment variables set by
set_ld_library_path_env_vars so that one can recreate the same
executable as "make check" run.

	PR testsuite/60590
	* lib/target-libpath.exp (set_ld_library_path_env_vars): Log
	LD_LIBRARY_PATH, LD_RUN_PATH, SHLIB_PATH, LD_LIBRARY_PATH_32,
	LD_LIBRARY_PATH_64 and DYLD_LIBRARY_PATH.

From-SVN: r208685