Here's and example code. I know it must be the line with 
pthread_cleanup_push() because the errors cease when I comment out this 
one line:

EXTERN_C
DWORD	naiBeginThread(	LPVOID			pSecurity,
			UINT		 	unStackSize, 
			void		 	(*pfStartAddr)(void *), 
			void		 	*pArgs,
			UINT			nInitFlag,
			LPDWORD			pdwThreadID)
{
   naiHandleObject_t	*hThread;
   int			nThreadID;

   // Create the thread object
   if ( (hThread = (naiHandleObject_t *)malloc(sizeof(naiHandleObject_t))) 
								== NULL)
   {
      nErrno = ENOMEM;
      return((DWORD)(-1));
   }
   if ( (hThread->Handle = (void *)malloc(sizeof(naiThread_t))) == NULL)
   {
      nErrno = ENOMEM;
      free(hThread);
      return((DWORD)(-1));
   }

   // Start the thread and set all the outbound data
   if ( (nThreadID = pthread_create((naiThread_t *)hThread->Handle,NULL,
		(void *(*) (void *)) pfStartAddr,
		pArgs)) != 0)
   {
      free(hThread->Handle);
      free(hThread);
      return((DWORD)(-1));
   }

   // Push on the clean up routines - memory is freed by naiCleanupThread()
   naiThreadCleanup_t	*pCleanup;
   if ( (pCleanup = (naiThreadCleanup_t *)
			malloc(sizeof(naiThreadCleanup_t))) == NULL)
      return((DWORD)(-1));
   pCleanup->Mutex = hThread->Mutex;
   pCleanup->Condition = hThread->Condition;
   pCleanup->bSignalled = &(hThread->bSignalled);
   pthread_cleanup_push(naiCleanupThread,(void *)pCleanup);

   // The caller must deal with this and convert it to HANDLE type
   if (pdwThreadID != NULL)
   {
      *pdwThreadID = nThreadID;
   }
   hThread->nType = naiOBJECT_THREAD;
   hThread->nReferenceCounter = 1;
   if (pthread_cond_init(&hThread->Condition,NULL) != 0)
   {
      free(hThread->Handle);
      free(hThread);
      return((DWORD)(-1));
   }
   if (pthread_mutex_init(&hThread->Mutex,NULL) != 0)
   {
      free(hThread->Handle);
      free(hThread);
      return((DWORD)(-1));
   }
   hThread->bSignalled = naiFALSE;
   return((DWORD)hThread);
}
//-------------------------------------------------------------------------
---

// Just like naiBeginThread() with the exceptions noted in the docs for 
that
// function.

EXTERN_C
HANDLE	naiCreateThread(	LPSECURITY_ATTRIBUTES	lpThreadAttributes,
				DWORD			dwStackSize,
				LPTHREAD_START_ROUTINE	lpStartAddress,
				LPVOID			lpParameter,
				DWORD			dwCreationFlags,
				LPDWORD			lpThreadId)
{
   HANDLE		*Handle;
   DWORD		dwRet;


   if ( (dwRet = naiBeginThread((LPVOID)lpThreadAttributes,dwStackSize,
			( void (*) (void *) )lpStartAddress,
			(void *)lpParameter,dwCreationFlags,
			lpThreadId)) == -1)
   {
      return(NULL);
   }
   memcpy(&Handle,&dwRet,4);
   return(Handle);
}

//-------------------------------------------------------------------------
---


Here are the compiler errors that are generated (BTW, the code above 
starts with line 1133):
gcc -c -fPIC -g -D_LINUX_REDHAT -I./source -I./include -I../source -
I../include -I../../linux/source -I../linux/include -I../../linux/source -
I../../linux/include -I../../source -I../../include -
o ../linux/bin/portable.o ../../linux/source/portable.cpp
../../linux/source/portable.cpp: In function `DWORD naiBeginThread 
(void *, unsigned int, void (*) (void *), void *, unsigned int, long 
unsigned int *)':
../../linux/source/portable.cpp:1172: parse error before string 
constant
../../linux/source/portable.cpp:1184: `lpThreadAttributes' undeclared 
(first use this function)
../../linux/source/portable.cpp:1184: (Each undeclared identifier is 
reported only once for each function it appears in.)
../../linux/source/portable.cpp:1184: `dwStackSize' undeclared (first 
use this function)
../../linux/source/portable.cpp:1185: `lpStartAddress' undeclared 
(first use this function)
../../linux/source/portable.cpp:1186: `lpParameter' undeclared (first 
use this function)
../../linux/source/portable.cpp:1186: `dwCreationFlags' undeclared 
(first use this function)
../../linux/source/portable.cpp:1187: `lpThreadId' undeclared (first 
use this function)
../../linux/source/portable.cpp:1189: warning: return to non-pointer type 
`DWORD' from NULL
../../linux/source/portable.cpp:1189: warning: argument to non-pointer 
type `long unsigned int' from 
NULL
../../linux/source/portable.cpp:1191: `Handle' undeclared (first use 
this function)