Remove -static-libgcc configure test.

Remove -static-libgcc configure test.

There is a configure test for -static-libgcc.  GCC added this option
in version 3.0, so this test is obsolete; this patch removes it.

Tested for x86_64 and x86 (testsuite, and that installed shared
libraries are unchanged by the patch).

	* configure.ac (libc_cv_gcc_static_libgcc): Remove configure test.
	* configure: Regenerated.
	* config.make.in (static-libgcc): Remove variable.
	* Makerules (build-shlib-helper): Use -static-libgcc instead of
	$(static-libgcc).
	(build-module-helper): Likewise.