re PR target/48053 (ICE in in build_int_cst_wide, when building cpu2000 galgel/equake/ammp/fma3d/sixtrack)

gcc/
	PR target/48053
	* config/rs6000/predicates.md (easy_vector_constant_add_self,
	easy_vector_constant_msb): Do not handle V2DImode and V2DFmode.
	* config/rs6000/rs6000.c (const_vector_elt_as_int): Add assert that
	mode is not V2DImode or V2DFmode.
	(vspltis_constant): Do not handle V2DImode and V2DFmode.
	(rs6000_expand_vector_init): Replace copy_to_reg with copy_to_mode_reg.
	* config/rs6000/rs6000.md (movdi_internal32): Allow setting VSX
	registers to 0.
	(movdi_internal64): Likewise.

gcc/testsuite/
	PR target/48053
	* gcc/testsuite/gcc.target/powerpc/pr48053-1.c: New test.
	* gcc/testsuite/gcc.target/powerpc/pr48053-2.c: Likewise.

From-SVN: r170920