[NFC] Factor out hasForceAttributes

[kyulee]

Summary

This is a preparation for https://reviews.llvm.org/D85586.

[plotfi]

LGTM

[kyulee]

@plotfi Can you commit this for me? Thanks in advance!

llvm/lib/Transforms/IPO/ForceFunctionAttrs.cpp

if (Kind == Attribute::None) {
       continue;
     }
     if (F.hasFnAttribute(Kind))
       continue;
     F.addFnAttr(Kind);
   }
 }
 
+static bool hasForceAttributes() { return !ForceAttributes.empty(); }
+
 PreservedAnalyses ForceFunctionAttrsPass::run(Module &M,
                                               ModuleAnalysisManager &) {
-  if (ForceAttributes.empty())
+  if (!hasForceAttributes())
     return PreservedAnalyses::all();
 
   for (Function &F : M.functions())
     addForcedAttributes(F);
 
   // Just conservatively invalidate analyses, this isn't likely to be important.
   return PreservedAnalyses::none();
 }