[lit] Simplify regex for dxil version check. (microsoft#6335)

Check dxc version and dxil version separately.

tools/clang/test/LitDXILValidation/illegalDXILOp.ll

@@ -39,7 +39,7 @@ define void @main() {
 
   %6 = call %dx.types.Handle @dx.op.annotateHandle2(i32 216, %dx.types.Handle %2, %dx.types.ResourceProperties { i32 32782, i32 0 })  ; AnnotateHandle(res,props)  resource: SamplerComparisonState
 
-; CHECK: error: DXILOpCode must be [0..258].  1999981 specified.
+; CHECK: error: DXILOpCode must be [0..{{[0-9]+}}].  1999981 specified.
 ; CHECK: note: at '%7 = call float @dx.op.calculateLOD.f32(i32 1999981, %dx.types.Handle %5, %dx.types.Handle %6, float %3, float %4, float undef, i1 true)' in block '#0' of function 'main'.
 
   %7 = call float @dx.op.calculateLOD.f32(i32 1999981, %dx.types.Handle %5, %dx.types.Handle %6, float %3, float %4, float undef, i1 true)  ; CalculateLOD(handle,sampler,coord0,coord1,coord2,clamped)

tools/clang/test/lit.cfg

@@ -507,12 +507,14 @@ if config.spirv:
 def get_dxil_version():
     result = subprocess.run([lit.util.which('dxc', llvm_tools_dir), "--version"], stdout=subprocess.PIPE)
     output = result.stdout.decode("utf-8")
-    pat = re.compile(r"(dxcompiler.dll|libdxcompiler.so|libdxcompiler.dylib): (?P<dxcMajor>[0-9]+)\.(?P<dxcMinor>[0-9]+).*(; (dxil.dll|libdxil.so): (?P<dxilMajor>[0-9]+)\.(?P<dxilMinor>[0-9]+))?")
-    m = pat.search(output)
+    dxcPat = re.compile(r"(dxcompiler.dll|libdxcompiler.so|libdxcompiler.dylib): (?P<dxcMajor>[0-9]+)\.(?P<dxcMinor>[0-9]+).")
+    m = dxcPat.search(output)
     dxcMajor = int(m.group("dxcMajor"))
     dxcMinor = int(m.group("dxcMinor"))
 
-    if None == m.group("dxilMajor"):
+    dxilPat = re.compile(r"; (dxil.dll|libdxil.so): (?P<dxilMajor>[0-9]+)\.(?P<dxilMinor>[0-9]+)")
+    m = dxilPat.search(output)
+    if None == m:
         return dxcMajor, dxcMinor
     dxilMajor = int(m.group("dxilMajor"))
     dxilMinor = int(m.group("dxilMinor"))