Fix typos.

Originally committed as revision 17927 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/random_seed.h

@@ -24,7 +24,7 @@
 #include <stdint.h>
 
 /**
- * Get a seed to use in conjuction with random functions
+ * Gets a seed to use in conjuction with random functions.
  */
 uint32_t ff_random_get_seed();