posix: Change sem_t to the 32-bit object type

This change is also valid for 16-bit object type architectures since in
this case POSIX_Semaphore_Control::Semaphore_id is used as a proxy.

cpukit/posix/include/semaphore.h

@@ -40,7 +40,7 @@ extern "C" {
 /*
  *  11.1 Semaphore Characteristics, P1003.1b-1993, p.219
  */
-typedef int sem_t;
+typedef uint32_t sem_t;
 
 /*
  *  Bad semaphore Id

cpukit/posix/src/semopen.c

@@ -139,6 +139,6 @@ return_id:
     the_semaphore->Semaphore_id = the_semaphore->Object.id;
     return &the_semaphore->Semaphore_id;
   #else
-    return (sem_t *)&the_semaphore->Object.id;
+    return &the_semaphore->Object.id;
   #endif
 }