re PR target/84772 (powerpc-spe: Spurious "is used uninitialized" warning, or possibly incorrect codegen for va_arg(long double))

	PR target/84772
	* config/rs6000/rs6000.c (rs6000_gimplify_va_arg): Mark va_arg_tmp
	temporary TREE_ADDRESSABLE before gimplification of BUILT_IN_MEMCPY.
	* config/powerpcspe/powerpcspe.c (rs6000_gimplify_va_arg): Likewise.

	* gcc.dg/pr84772.c: New test.

From-SVN: r258399