doc: ensure GCC_EXTRA_DIAGNOSTIC_OUTPUT gets an HTML anchor

This is referenced by my recent release notes changes for GCC 11:
  https://gcc.gnu.org/pipermail/gcc-patches/2021-January/564164.html

gcc/ChangeLog:
	* doc/invoke.texi (GCC_EXTRA_DIAGNOSTIC_OUTPUT): Add @findex
	directive.

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 99d25462e488eecf1088e98fbe2eff0e03b1e8e0..34218a751f0a741d17d683e1ad48b8df9d20c431 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -32750,6 +32750,7 @@ compiler uses @code{mblen} and @code{mbtowc} as defined by the default locale to
 recognize and translate multibyte characters.
 
 @item GCC_EXTRA_DIAGNOSTIC_OUTPUT
+@findex GCC_EXTRA_DIAGNOSTIC_OUTPUT
 If @env{GCC_EXTRA_DIAGNOSTIC_OUTPUT} is set to one of the following values,
 then additional text will be emitted to stderr when fix-it hints are
 emitted.  @option{-fdiagnostics-parseable-fixits} and