Make the string matching for 'frame variable' more stringent with respect to

output from clang and llvm-gcc compiled program; both generate the correct debug
info with respect to the typedef scoped inside a namespace.

Add a TestBase.getCompiler(self) method which returns the compiler in effect the
test suite is now running with.  Subclasses (like TestNamespace) can use it to
distinguish among different compilers.

llvm-svn: 119445