Error while installing: `php.h` not found

I am installing it on OSC 10.10 Yosemite. I already have MAMP installed. On running `make` I am getting:

```
In file included from ./protocolbuffers.h:34:
./php_protocolbuffers.h:41:10: fatal error: 'php.h' file not found
#include "php.h"
         ^
1 error generated.
make: *** [protocolbuffers.lo] Error 1
```
