Added extra calls to the UniqueCStringMap to allow it to be used

more efficiently when it contains a large number of items. Since
the map is actually a vector of "const char *" and type T values,
it will double in size every time you append to it. The extra
added functions allow the collection to be sized to fit the data
after all entries have been appended, and lookups by name or by
regex have been built in to the class to allow efficient lookup.

llvm-svn: 139477