Make sure that labeling is used consistently in all function headers.

libc/string/lib_stpcpy.c

@@ -52,7 +52,7 @@
  *   Copies the string pointed to by 'src' (including the terminating NUL
  *   character) into the array pointed to by 'dest'.
  *
- * Returned value:
+ * Returned Value:
  *   The stpcpy() function returns a pointer to the terminating NUL
  *   character copied into the 'dest' buffer
  *

libc/string/lib_strcpy.c

@@ -52,7 +52,7 @@
  *   Copies the string pointed to by 'src' (including the terminating NUL
  *   character) into the array pointed to by 'des'.
  *
- * Returned value:
+ * Returned Value:
  *   The strcpy() function returns the 'dest' pointer
  *
  ****************************************************************************/

libc/string/lib_strtok.c

@@ -75,7 +75,7 @@ static char *g_saveptr = NULL;
  *    end of the string are ignored.  The tokens returned by
  *    strtok() are always non-empty strings.
  *
- * Return
+ * Returned Value:
  *    strtok() returns a pointer to the next token, or NULL
  *    if there are no more tokens.
  *

libc/string/lib_strtokr.c

@@ -84,7 +84,7 @@
  *   end of the string are ignored.  The tokens returned by
  *   strtok() are always non-empty strings.
  *
- * Return
+ * Returned Value:
  *    strtok_r() returns a pointer to the next token, or NULL
  *    if there are no more tokens.
  *