core: remove build with autotools

CMake is now the only way to build WeeChat.

icons/Makefile.am

@@ -1,39 +0,0 @@
-#
-# Copyright (C) 2003-2023 Sébastien Helleu <flashcode@flashtux.org>
-#
-# This file is part of WeeChat, the extensible chat client.
-#
-# WeeChat is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 3 of the License, or
-# (at your option) any later version.
-#
-# WeeChat is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with WeeChat.  If not, see <https://www.gnu.org/licenses/>.
-#
-
-EXTRA_DIST = 16x16/weechat.png \
-             32x32/weechat.png \
-             64x64/weechat.png \
-             128x128/weechat.png \
-             256x256/weechat.png \
-             512x512/weechat.png
-
-icon16dir = $(datadir)/icons/hicolor/16x16/apps
-icon32dir = $(datadir)/icons/hicolor/32x32/apps
-icon64dir = $(datadir)/icons/hicolor/64x64/apps
-icon128dir = $(datadir)/icons/hicolor/128x128/apps
-icon256dir = $(datadir)/icons/hicolor/256x256/apps
-icon512dir = $(datadir)/icons/hicolor/512x512/apps
-
-icon16_DATA = 16x16/weechat.png
-icon32_DATA = 32x32/weechat.png
-icon64_DATA = 64x64/weechat.png
-icon128_DATA = 128x128/weechat.png
-icon256_DATA = 256x256/weechat.png
-icon512_DATA = 512x512/weechat.png