pax(1): Remove a few double words in source code comments

- s/an an/an/

MFC after:	3 days

bin/pax/cache.c

@@ -68,7 +68,7 @@ static GIDC **grptb = NULL;	/* group name to gid cache */
 
 /*
  * uidtb_start
- *	creates an an empty uidtb
+ *	creates an empty uidtb
  * Return:
  *	0 if ok, -1 otherwise
  */
@@ -92,7 +92,7 @@ uidtb_start(void)
 
 /*
  * gidtb_start
- *	creates an an empty gidtb
+ *	creates an empty gidtb
  * Return:
  *	0 if ok, -1 otherwise
  */
@@ -116,7 +116,7 @@ gidtb_start(void)
 
 /*
  * usrtb_start
- *	creates an an empty usrtb
+ *	creates an empty usrtb
  * Return:
  *	0 if ok, -1 otherwise
  */
@@ -140,7 +140,7 @@ usrtb_start(void)
 
 /*
  * grptb_start
- *	creates an an empty grptb
+ *	creates an empty grptb
  * Return:
  *	0 if ok, -1 otherwise
  */

sys/amd64/amd64/pmap.c

@@ -8042,7 +8042,7 @@ pmap_zero_page(vm_page_t m)
 }
 
 /*
- * Zero an an area within a single hardware page.  off and size must not
+ * Zero an area within a single hardware page.  off and size must not
  * cover an area beyond a single hardware page.
  */
 void