LoongArch: testsuite:Modify the test behavior of the vect-bic-bitmask-{12, 23}.c file.

Before modifying the test behavior of the program, dg-do is set to assemble in
vect-bic-bitmask-{12,23}.c. However, when the binutils library does not support
the vector instruction set, it will FAIL to recognize the vector instruction
and fail item will appear in the assembly stage. So set the program's dg-do to
compile.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/vect-bic-bitmask-12.c: Change the default
	setting of assembly to compile.
	* gcc.dg/vect/vect-bic-bitmask-23.c: Dito.

gcc/testsuite/gcc.dg/vect/vect-bic-bitmask-12.c

 /* { dg-skip-if "missing optab for vectorization" { sparc*-*-* } } */
-/* { dg-do assemble } */
+/* { dg-do compile } */
 /* { dg-additional-options "-O3 -fdump-tree-dce -w" } */
 
 #include <stdint.h>

gcc/testsuite/gcc.dg/vect/vect-bic-bitmask-23.c

 /* { dg-skip-if "missing optab for vectorization" { sparc*-*-* } } */
-/* { dg-do assemble } */
+/* { dg-do compile } */
 /* { dg-additional-options "-O1 -fdump-tree-dce -w" } */
 
 #include <stdint.h>