fix warning with gcc 4.5, improve code a bit

include/mediastreamer2/msqueue.h

@@ -74,12 +74,14 @@ MS2_PUBLIC void ms_queue_flush(MSQueue *q);
 MS2_PUBLIC void ms_queue_destroy(MSQueue *q);
 
 
-
+#define __mblk_set_flag(m,pos,bitval) \
+	(m)->reserved2=(m->reserved2 & ~(1<<pos)) | ((!!bitval)<<pos) 
+	
 #define mblk_set_timestamp_info(m,ts) (m)->reserved1=(ts);
 #define mblk_get_timestamp_info(m)    ((m)->reserved1)
-#define mblk_set_marker_info(m,bit)   (m)->reserved2=((m)->reserved2|bit& 0x1)
+#define mblk_set_marker_info(m,bit)   __mblk_set_flag(m,0,bit)
 #define mblk_get_marker_info(m)	      ((m)->reserved2&0x1) /*bit 1*/
-#define mblk_set_precious_flag(m,bit)    (m)->reserved2=(m)->reserved2|((bit & 0x1)<<1) /*use to prevent mirroring*/
+#define mblk_set_precious_flag(m,bit)    __mblk_set_flag(m,1,bit)  /*use to prevent mirroring*/
 #define mblk_get_precious_flag(m)    (((m)->reserved2)>>1 & 0x1) /*bit 2*/
 #define mblk_set_cseq(m,value) (m)->reserved2=(m)->reserved2| ((value&0xFFFF)<<16);	
 #define mblk_get_cseq(m) ((m)->reserved2>>16)