Detect apple M2 processor targets

[orf]

Summary

Currently on MacOS getHostCPUName only detects M1 processors and not M2 processors. The M2 CPU family is the following:

❯ sysctl hw.cpufamily
hw.cpufamily: -634136515

[orf]

I added @t.p.northover as a reviewer because of the changes he made here https://reviews.llvm.org/D134351. I've got no idea who else I should add, so apologies if this is the wrong person!

llvm/lib/TargetParser/Host.cpp

 #define CPUFAMILY_ARM_CYCLONE 0x37a09642
 #define CPUFAMILY_ARM_TYPHOON 0x2c91a47e
 #define CPUFAMILY_ARM_TWISTER 0x92fb37c8
 #define CPUFAMILY_ARM_HURRICANE 0x67ceee93
 #define CPUFAMILY_ARM_MONSOON_MISTRAL 0xe81e7ef6
 #define CPUFAMILY_ARM_VORTEX_TEMPEST 0x07d34b9f
 #define CPUFAMILY_ARM_LIGHTNING_THUNDER 0x462504d2
 #define CPUFAMILY_ARM_FIRESTORM_ICESTORM 0x1b588bb3
+#define CPUFAMILY_ARM_BLIZZARD_AVALANCHE 0xda33d83d
 
 StringRef sys::getHostCPUName() {
   uint32_t Family;
   size_t Length = sizeof(Family);
   sysctlbyname("hw.cpufamily", &Family, &Length, NULL, 0);
 
   switch (Family) {
   case CPUFAMILY_ARM_SWIFT:
StringRef sys::getHostCPUName() {
   case CPUFAMILY_ARM_MONSOON_MISTRAL:
     return "apple-a11";
   case CPUFAMILY_ARM_VORTEX_TEMPEST:
     return "apple-a12";
   case CPUFAMILY_ARM_LIGHTNING_THUNDER:
     return "apple-a13";
   case CPUFAMILY_ARM_FIRESTORM_ICESTORM:
     return "apple-m1";
+  case CPUFAMILY_ARM_BLIZZARD_AVALANCHE:
+    return "apple-m2";
   default:
     // Default to the newest CPU we know about.
-    return "apple-m1";
+    return "apple-m2";
   }
 }
 #elif defined(_AIX)
 StringRef sys::getHostCPUName() {
   switch (_system_configuration.implementation) {
   case POWER_4:
     if (_system_configuration.version == PV_4_3)
       return "970";