Make the port build with the upcoming Qt 4.8.x series.

Since 4.8.0 [1], Qt itself does not automatically include GLU's
headers and libraries with its OpenGL module, so applications which
relied on Qt to get these need to be adjusted.

This has also involved polishing the port Makefile a little. It
still needs a lot of love. For now:

• Remove the modeline from the beginning of the file. Add an
• explicit dependency on GLU via USE_GL=glu. Move the CXXFLAGS and
• LDFLAGS lines up in the file. Merge the two lines setting LDFLAGS.
• Fix the port's build system to use CXXFLAGS instead of CPPFLAGS for
• C++ compiler flags, so that we need not set FLAGS in MAKE_ARGS anymore.

[1] http://qt.gitorious.org/qt/qt/commit/e7eed096a0c33607a7a37baaf06e5952dc9d556b