Fix folding of vector mask EQ/NE expressions

Fix folding of vector mask EQ/NE expressions

fold_binary_loc assumed that if the type of the result wasn't a vector,
the operands wouldn't be either.  This isn't necessarily true for
EQ_EXPR and NE_EXPR of vector masks, which can return a single scalar
for the mask as a whole.

2018-01-13  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* fold-const.c (fold_binary_loc): Check the argument types
	rather than the result type when testing for a vector operation.

gcc/testsuite/
	* gcc.target/aarch64/sve/vec_bool_cmp_1.c: New test.
	* gcc.target/aarch64/sve/vec_bool_cmp_1_run.c: Likweise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@256616 138bc75d-0d04-0410-961f-82ee72b054a4