When looking for the template instantiation pattern of a templated entity,
consistently select the definition of the pattern if there is one. This means
we'll pick the same owning module when we start instantiating a template that
we'll later pick when determining which modules are visible during that
instantiation.
This reinstates r300650, reverted in r300659, with a fix for a regression
reported by Chandler after commit.
llvm-svn: 300938
Richard Smith