MetadataLoader upgradeCUVariables() - silence static analyzer dyn_cast_or_null<> null dereference warning. NFCI.
MetadataLoader upgradeCUVariables() - silence static analyzer dyn_cast_or_null<> null dereference warning. NFCI.

The static analyzer is warning about a potential null dereference, but we know that the source won't be null so just use dyn_cast, which will assert if the value somehow is actually null.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@373448 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm