libtool: Don't remove gcov *.gcno files (#15441)

The libtool bundled with PHP is outdated and deletes *.gcno files used by
gcov during the build process.

While this issue has already been resolved upstream [1], incorporating the
fix at this point may not be practical. Therefore, we attempt to apply a
fix to the current version.

This change will enable proper coverage output for third-party PHP
extensions.

[1]: https://github.com/autotools-mirror/libtool/blob/master/NEWS#L605

build/ltmain.sh

@@ -3467,7 +3467,7 @@ EOF
 	tempremovelist=`$echo "$output_objdir/*"`
 	for p in $tempremovelist; do
 	  case $p in
-	    *.$objext)
+	    *.$objext | *.gcno)
 	       ;;
 	    $output_objdir/$outputname | $output_objdir/$libname.* | $output_objdir/${libname}${release}.*)
 	       if test "X$precious_files_regex" != "X"; then