Documentation improvements.

Documentation improvements.

* doc/autoconf.texi (Looping constructs): s/recurses/repeats/.
(Evaluation Macros): Drop `1' suffix from metasyntax variable name
that preceeds @dots.  Improve wording.
(Text processing Macros): Drop `1' suffix from metasyntax variable
name that preceeds @dots.
(Number processing Macros): Drop `1' suffix from metasyntax
variable name that preceeds @dots.  Improve wording.
* lib/m4sugar/m4sugar.m4 (m4_cmp): Comment wording fix.
Suggested by Ralf Wildenhues.

Signed-off-by: Eric Blake <ebb9@byu.net>