[mips] Check that features required by built-ins are enabled

Now Clang does not check that features required by built-in functions
are enabled. That causes errors in the backend reported in PR44018.

This patch fixes this bug by checking that required features
are enabled.

This should fix PR44018.

Differential Revision: https://reviews.llvm.org/D70808
diff --git a/clang/lib/Basic/Targets/Mips.cpp b/clang/lib/Basic/Targets/Mips.cpp
index b9ab80d..ead5e91 100644
--- a/clang/lib/Basic/Targets/Mips.cpp
+++ b/clang/lib/Basic/Targets/Mips.cpp
@@ -213,7 +213,10 @@
 bool MipsTargetInfo::hasFeature(StringRef Feature) const {
   return llvm::StringSwitch<bool>(Feature)
       .Case("mips", true)
+      .Case("dsp", DspRev >= DSP1)
+      .Case("dspr2", DspRev >= DSP2)
       .Case("fp64", FPMode == FP64)
+      .Case("msa", HasMSA)
       .Default(false);
 }