ADDING SHARED MODULE SUPPORT TO A MODULE
In order to be useful, a self-contained extension must be loadable
as a shared module. I will explain now how you can add shared module
support to an existing module called foo.
1. In config.m4, use PHP_ARG_WITH/PHP_ARG_ENABLE. Then you will
automatically be able to use --with-foo=shared or
2. In config.m4, use PHP_EXTENSION(foo, $ext_shared) to enable
building the extension.
3. Add the following line to Makefile.in:
LTLIBRARY_SHARED_NAME = foo.la
4. Add the following lines to your C source file: