RISC-V: Fix missing implied Zicsr from Zve32x

RISC-V: Fix missing implied Zicsr from Zve32x

The Zve32x extension depends on the Zicsr extension.
Currently, enabling Zve32x alone does not automatically imply Zicsr in GCC.

gcc/ChangeLog:

	* common/config/riscv/riscv-common.cc: Add Zve32x depends on Zicsr

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/predef-19.c: set the march to rv64im_zve32x
	instead of rv64gc_zve32x to avoid Zicsr implied by g. Extra m is
	added to avoid current 'V' extension requires 'M' extension

Signed-off-by: Jerry Zhang Jian <jerry.zhangjian@sifive.com>