lots of errors from fmgr.h when I try to write a C UDF

Hi,
I had Postgres 9.3 setup and run successfully in Eclipse (MacOSX)
I am trying to write a C user-defined function:

*#include <fmgr.h>*
*...*
*#ifdef PG_MODULE_MAGIC*
*PG_MODULE_MAGIC;*
*#endif*
...

However, when I tried to compile the code:
*gcc -fpic -c* ...
It gave me a lot of errors and warnings from fmgr.h:

*.../Users/atpham/workspacecdt/pgsql/src/include/fmgr.h:59:2: error:
unknown type name 'MemoryContext'*
* MemoryContext fn_mcxt; /* memory context to store
fn_extra in */*
* ^*
*/Users/atpham/workspacecdt/pgsql/src/include/fmgr.h:71:2: error: unknown
type name 'Oid'*
* Oid fncollation; /* collation for function
to use */*
* ^*
*/Users/atpham/workspacecdt/pgsql/src/include/fmgr.h:72:2: error: unknown
type name 'bool'*
* bool isnull; /* function must set true
if result is NULL */*
...

*Any suggestion where I did it wrong?*
Thank you :)