* ld-shared/shared.exp: Run tests on rs6000*-*-aix* and

	* ld-shared/shared.exp: Run tests on rs6000*-*-aix* and
	powerpc*-*-aix*.  Add code to create appropriate exports files,
	and pass appropriate compilation flags, and test against
	appropriate expected output.
	* ld-shared/xcoff.dat: New file.
	* ld-shared/main.c: Put #ifndef XCOFF_TEST around tests that can
	not be linked using XCOFF.  Use shlib_shlibvar1 as a sample
	function pointer, rather than shlib_mainvar.
	* ld-shared/sh1.c: Likewise.
	* ld-shared/shared.dat: Update for change from using shlib_mainvar
	to using shlib_shlibvar1.
	* ld-shared/sun4.dat: Likewise.