[mlir][LLVM] erase call mappings in forgetMapping()

It looks like the mappings for call instructions were forgotten here.
This fixes a bug in OpenMP when inlining a region containing call
operations multiple times.

Author: tblah

mlir/lib/Target/LLVMIR/ModuleTranslation.cpp

@@ -716,6 +716,8 @@ void ModuleTranslation::forgetMapping(Region &region) {
           branchMapping.erase(&op);
         if (isa<LLVM::GlobalOp>(op))
           globalsMapping.erase(&op);
+        if (isa<LLVM::CallOp>(op))
+          callMapping.erase(&op);
         llvm::append_range(
             toProcess,
             llvm::map_range(op.getRegions(), [](Region &r) { return &r; }));