[boost] [python] patch for python.jam for HP-UX (setting proper file suffix)

On HP-UX, different versions of Python interpreter expect shared libraries to have different suffix: for example, Python 2.4.3 expects .sl suffix while Python 2.5 expects .so suffix. Attached patch makes sure that on HP-UX, boost python library tests create python extension files with the suffix appropriate for the version of Python interpreter used by the test system. I tested it on HP-UX with Python 2.4.3 and with Python 2.5. I also tested it on Tru64 to make sure that it does not affect other platforms. Please, apply it to CVS HEAD and the RC branch. Thanks, Boris