Give CXXBoolLiteralExpr a type (all expressions need a valid type).

This fixes the following:

******************** TEST 'Parser/cxx-bool.cpp' FAILED! ********************
Command:
clang -fsyntax-only Parser/cxx-bool.cpp
Output:
SemaExpr.cpp:731: failed assertion `!t.isNull() && "DefaultFunctionArrayConversion - missing type"'
Output/cxx-bool.cpp.out.script: line 1: 22697 Abort trap              clang -fsyntax-only Parser/cxx-bool.cpp

llvm-svn: 41401