MemoryBuiltins: getAllocAlignment is now useful for non-allocator funcs

This has been true since dba73135c8, but
didn't matter until now because clang wasn't emitting allocalign
attributes.

Differential Revision: https://reviews.llvm.org/D121640

llvm/lib/Analysis/MemoryBuiltins.cpp

@@ -334,8 +334,6 @@ bool llvm::isAllocRemovable(const CallBase *CB, const TargetLibraryInfo *TLI) {
 
 Value *llvm::getAllocAlignment(const CallBase *V,
                                const TargetLibraryInfo *TLI) {
-  assert(isAllocationFn(V, TLI));
-
   const Optional<AllocFnsTy> FnData = getAllocationData(V, AnyAlloc, TLI);
   if (FnData.hasValue() && FnData->AlignParam >= 0) {
     return V->getOperand(FnData->AlignParam);