Handle all TemplateArguments in trivial TypeLocs.

Armed with a much better understanding of what
TemplateSpecializationTypeLoc::initializeArgLocs actually does, I now
understand that it's fine to just use an empty TemplateArgumentLocInfo
for Integral, Declaration, and NullPtr TemplateArguments.

Fixes PR14281. (The testcases are actually derived from libcxx_test in
deduction-crash.cpp because the original testcase was impossible to reduce.)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185038 91177308-0d34-0410-b5e6-96231b3b80d8