- Issue #7714: Use ``gcc -dumpversion`` to detect the version of GCC on
  MacOSX.

- Make configure look for util.h as well as libutil.h. The former
  is the header file that on OSX contains the defition of openpty.

  (Needed to compile for OSX 10.4 on OSX 10.6)

- Use the correct definition of CC to compile the pythonw executable