Create a trigger in C on PostgreSQL 9

I have a PostgreSQL 9.0 server on Ubuntu 10.04, and I try to create an trigger in C code, following the next links:

Documentation, Compile

For the time being, my code should show only the value of the column in a record (and return the "edited" record):

#include "postgres.h"
#include "executor/spi.h"
#include "commands/trigger.h"

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

extern Datum trigger_test(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(trigger_test);

Datum
trigger_test(PG_FUNCTION_ARGS)
{
  TriggerData *trigdata = (TriggerData *) fcinfo->context;
  TupleDesc   tupdesc;
  HeapTuple   rettuple;

  if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
    rettuple = trigdata->tg_newtuple;
  else
    rettuple = trigdata->tg_trigtuple;

  tupdesc = trigdata->tg_relation->rd_att;

  bool isnull = false;
  int64 att = DatumGetInt64(heap_getattr(rettuple, 2, tupdesc, &isnull));

  elog(INFO,"Value second column is: %d",att);
  return PointerGetDatum(rettuple);
}

This file is in the same path of postgres.h and there are the files: executor/spi.h and commands/trigger.h. However, when I run the command:

cc -fpic -c trigger_test.c

I receive the errors:

In file included from postgres.h:48,
from trigger_test.c:1:
   utils/elog.h:69:28: error: utils/errcodes.h: Not exists the file or directory
In file included from trigger_test.c:2:
  executor/spi.h:16:30: error: nodes/parsenodes.h: Not exists the file or directory
  executor/spi.h:17:26: error: utils/portal.h: Not exists the file or directory
  executor/spi.h:18:28: error: utils/relcache.h: Not exists the file or directory
  executor/spi.h:19:28: error: utils/snapshot.h: Not exists the file or directory
...

All files exists and I don't want to change all includes in the files: elog.h, spi.h, etc, for the consequences that might have. Has anyone set up such triggers and can tell me where I'm wrong?

Thanks in advance.