Adjust gcc_release for id href web transformations

We now have some script which transforms e.g.
<h2 id="15.1">GCC 15.1</h2>
line in gcc-15/changes.html to
<h2 id="15.1"><a href="#15.1">GCC 15.1</a></h2>

This unfortunately breaks the gcc_release script, which looks for
GCC 15.1 appearing in gennews after optional blanks from the start of
the line in the NEWS file, which is no longer the case, there is
[129]GCC 15.1
or something like that with an URL later on
 129. https://gcc.gnu.org/gcc-15/changes.html#15.1

The following patch handles this.

2025-04-25  Jakub Jelinek  <[email protected]>

	* gcc_release: Allow optional \[[0-9]+\] before GCC major.minor
	in the NEWS file.

Author: jakubjelinek

maintainer-scripts/gcc_release

@@ -141,7 +141,7 @@ build_sources() {
 		 "in gcc-${RELEASE_MAJOR}/index.html"
 
     sed -n -e "/^${thischanges}/,/^${previndex}/p" NEWS |\
-	   grep -q "^[[:blank:]]*GCC ${RELEASE_MAJOR}.${RELEASE_MINOR}" ||\
+	   grep -q "^[[:blank:]]*\(\[[0-9]\{1,\}\][[:blank:]]*\)\{0,1\}GCC ${RELEASE_MAJOR}.${RELEASE_MINOR}" ||\
 	   error "GCC ${RELEASE_MAJOR}.${RELEASE_MINOR} not mentioned "\
 		 "in gcc-${RELEASE_MAJOR}/changes.html"