Module is now compiled into PHP

PHP extension template in Rust

This is port to Rust of what PHP script ext_skel generates in C

Shows how

• export Rust function to C
• have global C struct _zend_module_entry in Rust and pass pointer to C
• uses cdylib and prefer-dynamic (and link-arg=-undefined link-arg=dynamic_lookup on OSX)
• how to call Zend API from Rust
• how to port C Zend macro to Rust (e.g. RETURN_STR and PHP_FE_END)

TBC

$ php -d extension=./target/debug/libhello.dylib -f hello.php
Functions available in the test extension:
confirm_hello_compiled

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