IPO.h - remove unused llvm::Function forward declaration. NFC.

Author: RKSimon

llvm/include/llvm/Transforms/IPO.h

@@ -24,7 +24,6 @@ class StringRef;
 class ModuleSummaryIndex;
 class ModulePass;
 class Pass;
-class Function;
 class BasicBlock;
 class GlobalValue;
 class raw_ostream;