RISC-V: testsuite: restrict big endian test to non vector

RISC-V: testsuite: restrict big endian test to non vector

RISC-V vector currently does not support big endian so the postcommit
was getting the sorry, not implemented error on vector targets. Restrict
the testcase to non-vector targets

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/pr117595.c: Restrict to non vector targets.

Signed-off-by: Edwin Lu <ewlu@rivosinc.com>