RecursiveASTVisitor.h: Rework Doug's r160404, "Eliminating the GCC_CAST hack, take two."

With this, ARCMT tests would not crash on certain hosts with g++ -O2, eg. cygwin g++-4.5.3.

r160404 crashed mingw32-g++-4.4.0. I guess method's pointer in conditional expression could not be handled.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168295 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed