Why can configure.compiler be cc or gcc?

[Ryan Schmidt]

Why are “cc” and “gcc” valid values for configure.compiler?

We have a zillion portfiles that have special handling for clang compilers, usually implemented by checking [string match *clang* ${configure.compiler}]. But on Xcode 5, system cc and system gcc are both clang. So if a user chooses system cc or system gcc as their compiler, the compiler will be clang, but the string matches for clang will be false, which can lead to wrong behavior, such as:

https://trac.macports.org/ticket/41169