Fix a valgrind complaint "jump over uninit memory"

It is very weird, clang documentation says:
ASTContext::CreateTypeSourceInfo - Allocate an uninitialized TypeSourceInfo...
ASTContext::getTrivialTypeSourceInfo - Allocate a TypeSourceInfo where all locations...

We should use the getTrivialTypeSourceInfo all over the place...


git-svn-id: http://root.cern.ch/svn/root/trunk@49343 27541ba8-7e3a-0410-8455-c3a389f83636