varasm: Fix up ICE in narrowing_initializer_constant_valid_p [PR105998]

varasm: Fix up ICE in narrowing_initializer_constant_valid_p [PR105998]

The following testcase ICEs because there is NON_LVALUE_EXPR (location
wrapper) around a VAR_DECL and has TYPE_MODE V2SImode and
SCALAR_INT_TYPE_MODE on that ICEs.  Or for -m32 -march=i386 TYPE_MODE
is DImode, but SCALAR_INT_TYPE_MODE still uses the raw V2SImode and ICEs
too.

2022-06-18  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/105998
	* varasm.cc (narrowing_initializer_constant_valid_p): Check
	SCALAR_INT_MODE_P instead of INTEGRAL_MODE_P, also break on
	! INTEGRAL_TYPE_P and do the same check also on op{0,1}'s type.

	* c-c++-common/pr105998.c: New test.