Fix building extension from php-src/ext directory
Fix building extension from php-src/ext directory

When building extensions directly from the php-src/ext directory, for
example to build the extension statically into PHP directly, PHP header
files are located in the $abs_srcdir directory.

This patch adds additional check for checking file locations of the
socket extension.

Additional macro PHP_ADD_EXTENSION_DEP call is added for more proper
initialization order. In case, sockets extension is a dependency, it
must be initialized before swoole.

swoole/swoole-src,swoole/swoole-src,swoole/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src,LinkedDestiny/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src,LinkedDestiny/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src,LinkedDestiny/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src