Run make:

# make

...

Libraries have been installed in:
   /dat/dev/php/my_ext_name/modules

Test library:

# php -r 'dl("/dat/dev/php/my_ext_name/modules/my_ext_name.so");
          echo "\n".confirm_my_ext_name_compiled("my_ext_name")."\n";'

Output:

Congratulations! You have successfully modified ext/my_ext_name/config.m4. Module my_ext_name is now compiled into PHP.