[Support] Turn on SupportTest for Apple Silicon

[steven_wu]

Summary

Follow up for the fix for Apple Silicon, turn on unittest for Host on
Apple Silicon.

[dexonsmith]

LGTM.

[dexonsmith]

In D106020#2878494, @dexonsmith wrote:

LGTM.

BTW, often better to skip the Phab review if you're fixing a bot failure... and it'd be good to point at the original commit/review in the commit message.

llvm/unittests/Support/Host.cpp

class HostTest : public testing::Test {
   Triple Host;
 
 protected:
   bool isSupportedArchAndOS() {
     // Initially this is only testing detection of the number of
     // physical cores, which is currently only supported/tested on
     // some systems.
     return (Host.isOSWindows() && llvm_is_multithreaded()) ||
-           (Host.isX86() && (Host.isOSDarwin() || Host.isOSLinux())) ||
+           Host.isOSDarwin() || (Host.isX86() && Host.isOSLinux()) ||
            (Host.isPPC64() && Host.isOSLinux()) ||
            (Host.isSystemZ() && (Host.isOSLinux() || Host.isOSzOS()));
   }
 
   HostTest() : Host(Triple::normalize(sys::getProcessTriple())) {}
 };
 
 TEST_F(HostTest, NumPhysicalCores) {