Fix python detection code

Fix python detection code

Signed-off-by: Gilles Espinasse <g.esp@free.fr>
Compiling libnl versions that include doc or the git tree produce this
checking for python build information...
checking for python2.6... python2.6
checking for main in -lpython2.6... yes
checking python2.6/Python.h usability... yes
checking python2.6/Python.h presence... yes
checking for python2.6/Python.h... yes
./configure: line 4272: test: !=: unary operator expected
checking for python2.5... (cached) python2.6
checking for main in -lpython2.6... (cached) yes
checking for python2.6/Python.h... (cached) yes
./configure: line 4272: test: !=: unary operator expected
checking for python2.4... (cached) python2.6
checking for main in -lpython2.6... (cached) yes
checking for python2.6/Python.h... (cached) yes
./configure: line 4272: test: !=: unary operator expected
checking for python2.3... (cached) python2.6
checking for main in -lpython2.6... (cached) yes
checking for python2.6/Python.h... (cached) yes
./configure: line 4272: test: !=: unary operator expected
checking for python2.2... (cached) python2.6
checking for main in -lpython2.6... (cached) yes
checking for python2.6/Python.h... (cached) yes
./configure: line 4272: test: !=: unary operator expected
checking for python2.1... (cached) python2.6
checking for main in -lpython2.6... (cached) yes
checking for python2.6/Python.h... (cached) yes
./configure: line 4272: test: !=: unary operator expected
checking for python... (cached) python2.6
checking for main in -lpython2.6... (cached) yes
checking for python2.6/Python.h... (cached) yes
./configure: line 4272: test: !=: unary operator expected
  results of the Python check:
    Binary:      python2.6
    Library:     python2.6
    Include Dir: no

Fix the unary operator warning allow to break when one python version is found
Add the more recent python versions
Change send upstream as http://savannah.gnu.org/patch/index.php?7897
Signed-off-by: Thomas Graf <tgraf@suug.ch>