ntdll: Always use MAP_FAILED as mmap()'s error value.

dlls/ntdll/unix/virtual.c

@@ -1807,7 +1807,7 @@ static NTSTATUS map_file_into_view( struct file_view *view, int fd, size_t start
     /* only try mmap if media is not removable (or if we require write access) */
     if (!removable || (flags & MAP_SHARED))
     {
-        if (mmap( (char *)view->base + start, size, prot, flags, fd, offset ) != (void *)-1)
+        if (mmap( (char *)view->base + start, size, prot, flags, fd, offset ) != MAP_FAILED)
             goto done;
 
         switch (errno)
@@ -1970,7 +1970,7 @@ static NTSTATUS map_pe_header( void *ptr, size_t size, int fd, BOOL *removable )
 
     if (!*removable)
     {
-        if (mmap( ptr, size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_FIXED|MAP_PRIVATE, fd, 0 ) != (void *)-1)
+        if (mmap( ptr, size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_FIXED|MAP_PRIVATE, fd, 0 ) != MAP_FAILED)
             return STATUS_SUCCESS;
 
         switch (errno)