x11-libs/libdockapp: fix build with -fno-common

Actual failure is seen in packages using libdockapp, like
x11-plugins/wminet

Closes: https://bugs.gentoo.org/707484
Package-Manager: Portage-2.3.96, Repoman-2.3.21
Signed-off-by: Bernard Cafarelli <voyageur@gentoo.org>

x11-libs/libdockapp/files/libdockapp-0.7.2-fno-common.patch

@@ -0,0 +1,12 @@
+diff -Naur libdockapp-0.7.2.orig/src/wmgeneral.h libdockapp-0.7.2/src/wmgeneral.h
+--- libdockapp-0.7.2.orig/src/wmgeneral.h	2015-10-27 10:32:25.000000000 +0100
++++ libdockapp-0.7.2/src/wmgeneral.h	2020-03-28 14:33:25.070622841 +0100
+@@ -66,7 +66,7 @@
+  /* Global variable */
+ /*******************/
+ 
+-Display		*display;
++extern Display		*display;
+ 
+   /***********************/
+  /* Function Prototypes */

x11-libs/libdockapp/libdockapp-0.7.2-r1.ebuild

@@ -0,0 +1,46 @@
+# Copyright 1999-2020 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+inherit autotools font
+
+DESCRIPTION="Window Maker Dock Applet Library"
+HOMEPAGE="https://www.dockapps.net/libdockapp"
+SRC_URI="https://dev.gentoo.org/~voyageur/distfiles/${P}.tar.gz"
+
+LICENSE="MIT public-domain"
+SLOT="0/3"
+KEYWORDS="~alpha ~amd64 ~ppc ~ppc64 ~sparc ~x86"
+# Required for font eclass
+IUSE="+X"
+REQUIRED_USE="X"
+
+RDEPEND="x11-libs/libX11
+	x11-libs/libXt
+	x11-libs/libXext
+	x11-libs/libXpm"
+DEPEND="${RDEPEND}
+	x11-base/xorg-proto"
+
+FONT_S=${S}/fonts
+FONT_SUFFIX="gz"
+DOCS="README ChangeLog NEWS AUTHORS"
+PATCHES=( "${FILESDIR}"/${P}-fno-common.patch )
+
+src_prepare()
+{
+	default
+	eautoreconf
+}
+
+src_configure()
+{
+	# Font installation handled by font eclass
+	econf --without-font --without-examples
+}
+
+src_install()
+{
+	emake DESTDIR="${D}" install
+	font_src_install
+}