RISC-V: Fix riscv/arch-19.c with different ISA spec version

In newer ISA spec, F will implied zicsr, add that into -march option to
prevent different test result on different default -misa-spec version.

gcc/testsuite/

	* gcc.target/riscv/arch-19.c: Add -misa-spec.

gcc/testsuite/gcc.target/riscv/arch-19.c

 /* { dg-do compile } */
-/* { dg-options "-march=rv64if_zfinx -mabi=lp64" } */
+/* { dg-options "-march=rv64if_zicsr_zfinx -mabi=lp64" } */
 int foo() {}
-/* { dg-error "'-march=rv64if_zfinx': z\\*inx conflicts with floating-point extensions" "" { target *-*-* } 0 } */
+/* { dg-error "'-march=rv64if_zicsr_zfinx': z\\*inx conflicts with floating-point extensions" "" { target *-*-* } 0 } */