confused by m4_if description

[Ralf Wildenhues]

Hi Eric,

I always confuse m4_if with m4_case, and then start to wonder why m4_if
complains about excess arguments.  The patch below should help me
remember.  OK?

Thanks,
Ralf

    manual: clarify m4_if synopsis.
    
    * doc/autoconf.texi (Redefined M4 Macros): Rewrite synopsis of
    m4_if in the presence of more than three arguments.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 79a76da..7ec2528 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -10638,7 +10638,8 @@ This macro corresponds to @code{m4exit}.
 
 @defmac m4_if (@var{comment})
 @defmacx m4_if (@var{string-1}, @var{string-2}, @var{equal}, @ovar{not-equal})
address@hidden m4_if (@var{string-1}, @var{string-2}, @var{equal}, @dots{})
address@hidden m4_if (@var{string-1}, @var{string-2}, @var{equal-1}, @
+  @var{string-3}, @var{string-4}, @var{equal-2}, @dots{}, @ovar{not-equal})
 @msindex{if}
 This macro corresponds to @code{ifelse}.  @var{string-1} and
 @var{string-2} are compared literally, so usually one of the two