Add missing index entries to manual.

[Ralf Wildenhues]

Committed as obvious.  I've used something like

  exec 5<&0;
  sed -n 's/.*Macro: *\([^ ]*\) .*/\1/p' autoconf.info* |
  while read mac; do
    info -f ./autoconf.info --index $mac 0<&5;
  done

to find out manually which macros were defined but without index entry.
There's probably a better way to achieve that automatically.

Cheers,
Ralf

    Add missing index entries to manual.
    
    * doc/autoconf.texi (Fortran Compiler, Language Choice): Add
    index entries for AC_FC_DUMMY_MAIN, AC_LANG; reformat entry for
    AC_LANG_ASSERT.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index e510354..fac50b2 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -7886,6 +7886,8 @@ Fortran Compiler
 @defmacx AC_FC_DUMMY_MAIN (@ovar{action-if-found}, @ovar{action-if-not-found})
 @acindex{F77_DUMMY_MAIN}
 @cvindex F77_DUMMY_MAIN
address@hidden
address@hidden FC_DUMMY_MAIN
 With many compilers, the Fortran libraries detected by
 @code{AC_F77_LIBRARY_LDFLAGS} or @code{AC_FC_LIBRARY_LDFLAGS} provide
 their own @code{main} entry function that initializes things like
@@ -8503,6 +8505,7 @@ Language Choice
 
 @anchor{AC_LANG}
 @defmac AC_LANG (@var{language})
address@hidden
 Do compilation tests using the compiler, preprocessor, and file
 extensions for the specified @var{language}.
 
@@ -8576,8 +8579,9 @@ Language Choice
 @end defmac
 
 @defmac AC_LANG_ASSERT (@var{language})
address@hidden Check statically that the current language is
address@hidden  You should use this in your language specific macros
address@hidden
+Check statically that the current language is @var{language}.
+You should use this in your language specific macros
 to avoid that they be called with an inappropriate language.
 
 This macro runs only at @command{autoconf} time, and incurs no cost at