GCC probably prefers the 3.3 version if it's installed as the default that's run when you call 'python' without a version? You could always point that binary at the 2.7 to make it the default on your system..
Looking at the m4 source, seems like you might be able to do the following on one line:
PYTHON=/path/to/python2.7 PYTHON_INCLUDES="-I/usr/include/python2.7" ./configure --prefix /bla/bla