Revert "Another try to re-apply the StackPromotion commit 0dd045ca04dcc10a33abf57f7e1b08260c4e3de1."

This reverts commit 7d70aa39dc because
it may be responsible for a bot breakage.

tools/swift-llvm-opt/LLVMOpt.cpp

@@ -234,7 +234,6 @@ int main(int argc, char **argv) {
   initializeSwiftRCIdentityPass(Registry);
   initializeSwiftARCOptPass(Registry);
   initializeSwiftARCContractPass(Registry);
-  initializeSwiftStackPromotionPass(Registry);
 
   llvm::cl::ParseCommandLineOptions(argc, argv, "Swift LLVM optimizer\n");