Explain why there are no multiple inclusion guards in these header files.

Originally committed as revision 10771 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/i386/dsputil_mmx_avg.h

@@ -24,6 +24,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/* This header intentionally has no multiple inclusion guards. It is meant to
+ * be included multiple times and generates different code depending on the
+ * value of certain #defines. */
+
 /* XXX: we use explicit registers to avoid a gcc 2.95.2 register asm
    clobber bug - now it will work with 2.95.2 and also with -fPIC
  */

libavcodec/i386/dsputil_mmx_qns.h

@@ -22,6 +22,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/* This header intentionally has no multiple inclusion guards. It is meant to
+ * be included multiple times and generates different code depending on the
+ * value of certain #defines. */
+
 #define MAX_ABS (512 >> (SCALE_OFFSET>0 ? SCALE_OFFSET : 0))
 
 static int DEF(try_8x8basis)(int16_t rem[64], int16_t weight[64], int16_t basis[64], int scale)

libavcodec/i386/dsputil_mmx_rnd.h

@@ -24,6 +24,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/* This header intentionally has no multiple inclusion guards. It is meant to
+ * be included multiple times and generates different code depending on the
+ * value of certain #defines. */
+
 // put_pixels
 static void DEF(put, pixels8_x2)(uint8_t *block, const uint8_t *pixels, int line_size, int h)
 {