build: conditional define of struct prctl_mm_map

The file include/prctl.h should define the struct prctl_mm_map only if
it is not already defined in the system include file linux/prctl.h.

The definition should be part of the '#ifndef PR_SET_MM_MAP' block
since this structure is not defined in that case.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Reviewed-by: Christopher Covington <cov@codeaurora.org>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

include/prctl.h

@@ -51,7 +51,6 @@
 #ifndef PR_SET_MM_MAP
 # define PR_SET_MM_MAP			14
 # define PR_SET_MM_MAP_SIZE		15
-#endif
 
 struct prctl_mm_map {
 	u64	start_code;
@@ -69,6 +68,7 @@ struct prctl_mm_map {
 	u32	auxv_size;
 	u32	exe_fd;
 };
+#endif
 
 #ifndef PR_GET_TID_ADDRESS
 # define PR_GET_TID_ADDRESS	40