[embedded] Make sure to drop all references before deleting functions and globals in DropAllSILPass

Author: kubamracek

lib/SILOptimizer/UtilityPasses/DropAllSILPass.cpp

@@ -30,10 +30,12 @@ class DropAllSILPass : public SILModuleTransform {
     llvm::SmallVector<SILGlobalVariable *, 16> GlobalsToErase;
 
     for (SILFunction &F : M) {
+      F.dropAllReferences();
       FunctionsToErase.push_back(&F);
     }
 
     for (SILGlobalVariable &G : M.getSILGlobals()) {
+      G.dropAllReferences();
       GlobalsToErase.push_back(&G);
     }