FindPyKDE4: Make PYKDE4_INSTALL_PYTHON_FILES use PYTHON_INSTALL.

Commit 94f1d2fa ("PythonMacros: specify destination directory in
byte-compiled files") broke Kajongg's build because it uses the
PYKDE4_INSTALL_PYTHON_FILES() macro, whose use of PythonCompile.py had
not been updated.

Instead of just passing --destination-dir in FindPyKDE4.cmake, rewrite
the PYKDE4_INSTALL_PYTHON_FILES() macro to use PythonMacros's
PYTHON_INSTALL(). Not only does this fix Kajongg's build, but it also
removes a lot of code duplication and makes
PYKDE4_INSTALL_PYTHON_FILES() work with Python 3.2+'s different .pyc
location.

REVIEW:		126413