RISC-V: XFail the signbit-5 run test for RVV

RISC-V: XFail the signbit-5 run test for RVV

This patch would like to XFail the signbit-5 run test case for
the RVV.  Given the case has one limitation like "This test does not
work when the truth type does not match vector type." in the beginning
of the test file.  Aka, the RVV vector truth type is not integer type.

The target board of riscv-sim like below will pick up `-march=rv64gcv`
when building the run test elf. Thus, the RVV cannot bypass this test
case like aarch64_sve with additional option `-march=armv8-a`.

  riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow

For RVV, we leverage dg-xfail-run-if for this case like `amdgcn`.

The signbit-5.c passed test with below configurations but we need
further investigation for the failures of other configurations.

* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl1024b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl256b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=dynamic/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m2/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m4/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-lmul=m8/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64gcv_zvl512b/-mabi=lp64d/-mcmodel=medlow/--param=riscv-autovec-preference=fixed-vlmax
* riscv-sim/-march=rv64imafdcv/-mabi=lp64d/-mcmodel=medlow

gcc/testsuite/ChangeLog:

	* gcc.dg/signbit-5.c: XFail for the riscv_v.

Signed-off-by: Pan Li <pan2.li@intel.com>