I do not have any experience compiling PHP to ELF executables, but you can try http://php4mono.sourceforge.net or similar projects (IronPHP 0.0.1) to compile PHP to Common Intermediate Language (.NET/Mono bytecode) and run on .NET or Mono VMs. Mono 2 also now offers full ahead-of-time compilation with the --aot switch, so you may be able to jigger that up to produce a native executable. Worth a try, perhaps -- Mono is really cool and even if this doesn't work, it's good to learn more about Mono.
Good luck.
EDIT: Per your comment on numberwhun's post, I don't know of anything that will translate your PHP to C. There are such programs available for Python, however: Cython and Pyrex. If your application is somewhat trivial, perhaps a port is not out of the question.