Perform placeholder conversions on the controller of a _Generic
expression.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174930 91177308-0d34-0410-b5e6-96231b3b80d8
Remove an assert which triggers when a decl context in a module hits the 'has
lexical storage but not visible storage' case in C++. It's unclear whether we
even need the special-case handling for C++, since it seems to be working
around our not serializing a lookup table for the TU in C. But in any case,
the assertion is incorrect.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174931 91177308-0d34-0410-b5e6-96231b3b80d8