[libclang] Protect against the declaration's SourceRange being invalid
before passing to RangeCompare.

Though no idea how this can occur with the decls returned from
findFileRegionDecls().

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145301 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed