RISC-V] add TC for save-restore cfi directives.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/save-restore-cfi.c: New test to check save-restore
	cfi directives.

gcc/testsuite/gcc.target/riscv/save-restore-cfi.c

+/* { dg-do compile } */
+/* { dg-options "-g -Os -march=rv32imafc -mabi=ilp32f -msave-restore -mcmodel=medlow" } */
+/* { dg-skip-if "" { *-*-* } {"-O2" "-O1" "-O0" "-Og" "-O3" "-Oz" "-flto"} } */
+/* { dg-final { scan-assembler-times {\.cfi_def_cfa_offset 16} 2} } */
+/* { dg-final { scan-assembler-times {\.cfi_def_cfa_offset 32} 1} } */
+/* { dg-final { scan-assembler-times {\.cfi_def_cfa_offset 0} 1} } */
+
+char my_getchar();
+float getf();
+
+int foo()
+{
+  int s0 = my_getchar();
+  float f0 = getf();
+  int b = my_getchar();
+  return f0 + s0 + b;
+}