It was discovered that running "make clean" from a port with a dependency
on gcc31 or gcc32 (either with a BUILD_DEPENDS or via USE_GCC) with that
version of gcc already installed causes infinite recursion problems.
The issue stems from gcc31 and gcc32 using USE_GCC internally. Internally,
it was used to override any other definition and say that you can use any
gcc version to build gcc31/gcc32. But that USE_GCC redefinition was causing
recursion errors, so handle the problem instead by just simply undefining
USE_GCC inside the gcc port Makefile itself.
This should make things happy again.