remove some GNUisms. by Dan Fandrich (dan AT coneharvesters.com)

function                                             old     new   delta
logdirs_reopen                                      1310    1308      -2
read_line_input                                     4757    4753      -4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-6)               Total: -6 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/include/libbb.h b/include/libbb.h
index c795e6a..9f7c260 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1479,7 +1479,7 @@
 /* At least gcc 3.4.6 on mipsel system needs optimization barrier */
 #define barrier() __asm__ __volatile__("":::"memory")
 #define SET_PTR_TO_GLOBALS(x) do { \
-	(*(struct globals**)&ptr_to_globals) = (x); \
+	(*(struct globals**)&ptr_to_globals) = (void*)(x); \
 	barrier(); \
 } while (0)