[AArch64]: Refactor target parser to use Bitset. (#65423)

Use Bitset instead of BitMasking for the Architecture Extensions,
as the number of extensions will exceed the bitmask bits eventually.

Author: hassnaaHamdi

clang/lib/Basic/Targets/AArch64.cpp

@@ -979,7 +979,7 @@ bool AArch64TargetInfo::initFeatureMap(
   // Parse the CPU and add any implied features.
   std::optional<llvm::AArch64::CpuInfo> CpuInfo = llvm::AArch64::parseCpu(CPU);
   if (CpuInfo) {
-    uint64_t Exts = CpuInfo->getImpliedExtensions();
+    llvm::Bitset Exts = CpuInfo->getImpliedExtensions();
     std::vector<StringRef> CPUFeats;
     llvm::AArch64::getExtensionFeatures(Exts, CPUFeats);
     for (auto F : CPUFeats) {

clang/lib/Driver/ToolChains/Arch/AArch64.cpp

@@ -158,7 +158,7 @@ static bool DecodeAArch64Mcpu(const Driver &D, StringRef Mcpu, StringRef &CPU,
 
     Features.push_back(ArchInfo->ArchFeature);
 
-    uint64_t Extension = CpuInfo->getImpliedExtensions();
+    llvm::Bitset Extension = CpuInfo->getImpliedExtensions();
     if (!llvm::AArch64::getExtensionFeatures(Extension, Features))
       return false;
   }