Merge commit 87f3407856e6 from llvm-project (by Phoebe Wang):

  [X86][Driver] Do not add `-evex512` for `-march=native` when the target doesn't support AVX512 (#91694)

This prevents problems with ports that fail to build with
CPUTYPE=native, if the native CPU supports AVX512F, resulting in errors
like:

  /wrkdirs/usr/ports/archivers/libdeflate/work/libdeflate-1.20/lib/x86/adler32_template.h:197:21: error: always_inline function '_mm512_set1_epi8' requires target feature 'evex512', but would be inlined into function 'adler32_x86_avx512_vl512_vnni' that is compiled without support for 'evex512'
    197 |         const vec_t ones = VSET1_8(1);
        |                            ^
  /wrkdirs/usr/ports/archivers/libdeflate/work/libdeflate-1.20/lib/x86/adler32_template.h:116:23: note: expanded from macro 'VSET1_8'
    116 | #  define VSET1_8(a)            _mm512_set1_epi8(a)
        |                                 ^
  /wrkdirs/usr/ports/archivers/libdeflate/work/libdeflate-1.20/lib/x86/adler32_template.h:197:21: error: AVX vector return of type '__m512i' (vector of 8 'long long' values) without 'evex512' enabled changes the ABI
  /wrkdirs/usr/ports/archivers/libdeflate/work/libdeflate-1.20/lib/x86/adler32_template.h:116:23: note: expanded from macro 'VSET1_8'
    116 | #  define VSET1_8(a)            _mm512_set1_epi8(a)
        |                                 ^

Ports known to be affected are: archivers/libdeflate, devel/highway,
www/node20, and lang/rust.

(For rust itself there is also a similar issue reported at
rust-lang/rust#121088).

PR:		276104
Reported by:	netchild
MFC after:	3 days

(cherry picked from commit fcfb2d6)

contrib/llvm-project/llvm/lib/TargetParser/Host.cpp

@@ -1774,7 +1774,8 @@ bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
   Features["rtm"]        = HasLeaf7 && ((EBX >> 11) & 1);
   // AVX512 is only supported if the OS supports the context save for it.
   Features["avx512f"]    = HasLeaf7 && ((EBX >> 16) & 1) && HasAVX512Save;
-  Features["evex512"]    = Features["avx512f"];
+  if (Features["avx512f"])
+    Features["evex512"]  = true;
   Features["avx512dq"]   = HasLeaf7 && ((EBX >> 17) & 1) && HasAVX512Save;
   Features["rdseed"]     = HasLeaf7 && ((EBX >> 18) & 1);
   Features["adx"]        = HasLeaf7 && ((EBX >> 19) & 1);