Improve conditional checking during template instantiation.

When the condition in an if statement, while statement, or for loop is created
during template instantiation, it calls MakeFullExpr with only the condition
expression.  However, when these conditions are created for non-templated
code in the Parser, an additional SourceLocation is passed to MakeFullExpr.
The impact of this was that non-dependent templated code could produce
diagnostics that the same code outside templates would not.  Adding the missing
SourceLocation makes diagnostics consistent between templated and non-templated
code.

llvm-svn: 256976