sysconf: Remove sysconf(515)

GCC originally needed this 20 years ago. No longer needed, so it
is being removed.

Closes #4391

cpukit/posix/src/sysconf.c

@@ -54,10 +54,6 @@ long sysconf(
       return (long) rtems_scheduler_get_processor_maximum();
     case _SC_POSIX_26_VERSION:
       return (long) _POSIX_26_VERSION;
-#if defined(__sparc__)
-    case 515: /* Solaris _SC_STACK_PROT */
-      return 0;
-#endif
     default:
       rtems_set_errno_and_return_minus_one( EINVAL );
   }

testsuites/psxtests/psxsysconf/init.c

@@ -83,14 +83,6 @@ void *POSIX_Init(
       == (long) rtems_scheduler_get_processor_maximum()
   );
 
-#if defined(__sparc__)
-  /* Solaris _SC_STACK_PROT - 515 */
-  sc = sysconf( _SC_PAGESIZE );
-  printf( "sysconf - (SPARC only) _SC_STACK_PROT=%ld\n", sc );
-  if ( sc == -1 )
-   rtems_test_exit(0);
-#endif
-
   TEST_END();
   rtems_test_exit( 0 );