[Driver] Mark m_x86_Features_Group options as TargetSpecific

so that they lead to an error when compiled for non-x86 targets.
Follow-up to D151590.

```
% aarch64-linux-gnu-gcc -c -mavx a.c
aarch64-linux-gnu-gcc: error: unrecognized command-line option ‘-mavx’
% clang --target=aarch64-unknown-linux-gnu -c -mavx a.c  # without this patch
clang: warning: argument unused during compilation: '-mavx' [-Wunused-command-line-argument]
...

% clang --target=aarch64-unknown-linux-gnu -c -mavx a.c  # with this patch
clang: error: unsupported option '-mavx' for target 'aarch64-unknown-linux-gnu'
```

As a workaround for llvm#63270, we don't
report an error for -msse4.2.

Reviewed By: pengfei, skan

Differential Revision: https://reviews.llvm.org/D156962

Author: MaskRay

clang/include/clang/Driver/Options.td

@@ -4890,6 +4890,7 @@ foreach i = {0-7} in
 } // let Flags = [TargetSpecific]
 
 // X86 feature flags
+let Flags = [TargetSpecific] in {
 def mx87 : Flag<["-"], "mx87">, Group<m_x86_Features_Group>;
 def mno_x87 : Flag<["-"], "mno-x87">, Group<m_x86_Features_Group>;
 def m80387 : Flag<["-"], "m80387">, Alias<mx87>;
@@ -4923,7 +4924,11 @@ def mssse3 : Flag<["-"], "mssse3">, Group<m_x86_Features_Group>;
 def mno_ssse3 : Flag<["-"], "mno-ssse3">, Group<m_x86_Features_Group>;
 def msse4_1 : Flag<["-"], "msse4.1">, Group<m_x86_Features_Group>;
 def mno_sse4_1 : Flag<["-"], "mno-sse4.1">, Group<m_x86_Features_Group>;
+} // let Flags = [TargetSpecific]
+// TODO: Make -msse4.2 TargetSpecific after
+// https://github.com/llvm/llvm-project/issues/63270 is fixed.
 def msse4_2 : Flag<["-"], "msse4.2">, Group<m_x86_Features_Group>;
+let Flags = [TargetSpecific] in {
 def mno_sse4_2 : Flag<["-"], "mno-sse4.2">, Group<m_x86_Features_Group>;
 def msse4 : Flag<["-"], "msse4">, Alias<msse4_2>;
 // -mno-sse4 turns off sse4.1 which has the effect of turning off everything
@@ -5104,6 +5109,7 @@ def mretpoline_external_thunk : Flag<["-"], "mretpoline-external-thunk">, Group<
 def mno_retpoline_external_thunk : Flag<["-"], "mno-retpoline-external-thunk">, Group<m_x86_Features_Group>;
 def mvzeroupper : Flag<["-"], "mvzeroupper">, Group<m_x86_Features_Group>;
 def mno_vzeroupper : Flag<["-"], "mno-vzeroupper">, Group<m_x86_Features_Group>;
+} // let Flags = [TargetSpecific]
 
 // These are legacy user-facing driver-level option spellings. They are always
 // aliases for options that are spelled using the more common Unix / GNU flag

clang/test/Driver/x86-target-features.c

@@ -374,6 +374,13 @@
 // CRC32: "-target-feature" "+crc32"
 // NO-CRC32: "-target-feature" "-crc32"
 
+// RUN: not %clang -### --target=aarch64 -mcrc32 -msse4.1 -msse4.2 -mno-sgx %s 2>&1 | FileCheck --check-prefix=NONX86 %s
+// NONX86:      error: unsupported option '-mcrc32' for target 'aarch64'
+// NONX86-NEXT: error: unsupported option '-msse4.1' for target 'aarch64'
+/// TODO: This warning is a workaround for https://github.com/llvm/llvm-project/issues/63270
+// NONX86-NEXT: warning: argument unused during compilation: '-msse4.2' [-Wunused-command-line-argument]
+// NONX86-NEXT: error: unsupported option '-mno-sgx' for target 'aarch64'
+
 // RUN: %clang --target=i386 -march=i386 -mharden-sls=return %s -### -o %t.o 2>&1 | FileCheck -check-prefixes=SLS-RET,NO-SLS %s
 // RUN: %clang --target=i386 -march=i386 -mharden-sls=indirect-jmp %s -### -o %t.o 2>&1 | FileCheck -check-prefixes=SLS-IJMP,NO-SLS %s
 // RUN: %clang --target=i386 -march=i386 -mharden-sls=none -mharden-sls=all %s -### -o %t.o 2>&1 | FileCheck -check-prefixes=SLS-IJMP,SLS-RET %s