libtool upgrade to 2.4.6 - 4/n: fix m4 quoting bug

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=41837
http://git.savannah.gnu.org/gitweb/?p=libtool.git;a=commitdiff;h=0904164dd5b57b3230dce04207738ce961591762

acinclude/libtool.m4

@@ -5039,7 +5039,7 @@ dnl Note also adjust exclude_expsyms for C++ above.
       _LT_TAGVAR(whole_archive_flag_spec, $1)=
     fi
     supports_anon_versioning=no
-    case `$LD -v | $SED -e 's/([^)]\+)\s\+//' 2>&1` in
+    case `$LD -v | $SED -e 's/([[^)]]\+)\s\+//' 2>&1` in
       *GNU\ gold*) supports_anon_versioning=yes ;;
       *\ [[01]].* | *\ 2.[[0-9]].* | *\ 2.10.*) ;; # catch versions < 2.11
       *\ 2.11.93.0.2\ *) supports_anon_versioning=yes ;; # RH7.3 ...