aclocal.m4: Include acx.m4 and no-executables.m4.

	* aclocal.m4: Include acx.m4 and no-executables.m4.
	(libiberty_AC_FUNC_STRNCMP): Use AC_LIBOBJ.
	(LIB_AC_PROG_CC): Remove.
	* configure.in: Update AC_PREREQ to 2.57.  Use GCC_NO_EXECUTABLES.
	Use AC_PROG_CC and set ac_libiberty_warn_cflags instead of using
	LIB_AC_PROG_CC.  Use AC_LIBOBJ.  Call AC_ISC_POSIX later, only if
	performing link tests.
	* configure: Regenerated.

From-SVN: r70860