Make tilegx32 install libraries in lib32 directories.

This patch makes tilegx32 install libraries in lib32 directories,
matching what GCC expects and avoiding conflict with 64-bit libraries
installed in lib directories.

Tested (compilation only) for tilegx (32-bit and 64-bit, BE and LE,
GCC 5).

	* sysdeps/unix/sysv/linux/tile/tilegx/configure.ac: Use
	LIBC_SLIBDIR_RTLDDIR for tilegx32.
	* sysdeps/unix/sysv/linux/tile/tilegx/configure: Regenerated.