manual: index strings containing colon in non-info outputs.

[Ralf Wildenhues]

Tested 'make info ps pdf html' with texinfo 4.13 and 'make info' with
texinfo 4.11 on MinGW, checked the resulting outputs to work fine.  OK?

Thanks,
Ralf

    manual: index strings containing colon in non-info outputs.
    
    * doc/autoconf.texi (Quadrigraphs, Shell Substitutions): Produce
    index entries for concepts containing a colon in output formats
    other than info.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 3e2e51f..b42ae73 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -10280,11 +10280,13 @@ the one they were implemented with.
 @cindex @samp{@@S|@@}
 @cindex @samp{@@&t@@}
 @c Info cannot handle `:' in index entries.
address@hidden @cindex @samp{@@<:@@}
address@hidden @cindex @samp{@@:>@@}
address@hidden @cindex @samp{@@%:@@}
address@hidden @cindex @samp{@@@{:@@}
address@hidden @cindex @samp{@@:@}@@}
address@hidden
address@hidden @samp{@@<:@@}
address@hidden @samp{@@:>@@}
address@hidden @samp{@@%:@@}
address@hidden @samp{@@@{:@@}
address@hidden @samp{@@:@}@@}
address@hidden ifnotinfo
 
 When writing an Autoconf macro you may occasionally need to generate
 special characters that are difficult to express with the standard
@@ -15181,7 +15183,9 @@ bad substitution
 
 @item address@hidden@var{var}:address@hidden@}
 @c Info cannot handle `:' in index entries.
address@hidden @cindex address@hidden@var{var}:address@hidden@}
address@hidden
address@hidden address@hidden@var{var}:address@hidden@}
address@hidden ifnotinfo
 Old @acronym{BSD} shells, including the Ultrix @code{sh}, don't accept the
 colon for any shell substitution, and complain and die.
 Similarly for address@hidden@var{var}:address@hidden@}, 
address@hidden@var{var}:address@hidden@}, etc.