DebugInfo: Support up to 2^16 arguments in a subprogram

Support up to 2^16 arguments to a function.  If we do hit the limit,
assert out rather than restarting at 0 as we've done historically.

This fixes PR23332.  A clang test will follow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235955 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed