Thanks for all the help so far Roberto.

When I run

python uwsgiconfig.py --plugin plugins/php
using profile: buildconf/default.ini
detected include path: ['/usr/lib/gcc/x86_64-linux-gnu/4.6.1/include', '/usr/local/include', '/usr/lib/gcc/x86_64-linux-gnu/4.6.1/include-fixed', '/usr/include/x86_64-linux-gnu', '/usr/include']
*** uWSGI building and linking plugin plugins/php ***
[gcc -pthread] ./php_plugin.so
/usr/bin/ld: cannot find -lphp5
collect2: ld returned 1 exit status
*** unable to build php plugin ***