add multiple inclusion guards to headers

Originally committed as revision 9345 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/sparc/vis.h

@@ -40,6 +40,9 @@
  * the assembler to keep the binary from becoming tainted.
  */
 
+#ifndef AVCODEC_VIS_H
+#define AVCODEC_VIS_H
+
 #define vis_opc_base    ((0x1 << 31) | (0x36 << 19))
 #define vis_opf(X)      ((X) << 5)
 #define vis_sreg(X)     (X)
@@ -325,3 +328,5 @@ static inline void vis_alignaddrl_g0(void *_ptr)
 /* Pixel component distance.  */
 
 #define vis_pdist(rs1,rs2,rd)           vis_dd2d(0x3e, rs1, rs2, rd)
+
+#endif