media-sound/zynaddsubfx: add binding := to fltk & fix build with 1.4

1.4.x seems to have dropped some transitive includes, and this needs
to include what it uses.

:= due to new soname

Have not tried wayland (new in fltk-1.4), but given the build fix
revealed that it uses some X-specific bits, odds are it'll be
broken without fltk[X(+)] and so added that as well.

~arch version dropped fltk so this is just for stable, but had to
do a no-op ~arch revbump only to prevent the stable revbump from
becoming a higher revision.

Signed-off-by: Ionen Wolkens <ionen@gentoo.org>

media-sound/zynaddsubfx/files/zynaddsubfx-3.0.6-fltk1.4.patch

@@ -0,0 +1,20 @@
+MasterUI.cxx:2377:3: error: 'fl_open_display' was not declared ...
+
+Other files are using x.H, but that header is deprecated and the
+correct one is platform.H. fl_display that it alse needs platform.H
+for is X-specific, so this likely cannot work without fltk[X] at
+the moment.
+
+(next revision of the ebuild removes fltk, so it won't matter much)
+--- a/src/UI/MasterUI.fl
++++ b/src/UI/MasterUI.fl
+@@ -76,6 +76,9 @@
+ decl {\#include "common.H"} {public local
+ } 
+ 
++decl {\#include "FL/platform.H"} {public local
++} 
++
+ decl {\#if USE_NSM
+ \#include "NSM.H"
+ extern NSM_Client *nsm;

media-sound/zynaddsubfx/zynaddsubfx-3.0.6-r5.ebuild

@@ -24,7 +24,7 @@ DEPEND="
 	doc? ( dev-texlive/texlive-fontutils )
 	dssi? ( media-libs/dssi )
 	fltk? (
-		x11-libs/fltk:1
+		x11-libs/fltk:1=[X(+)]
 		x11-libs/libX11
 		x11-libs/libXpm
 	)
@@ -42,6 +42,7 @@ BDEPEND="
 PATCHES=(
 	"${FILESDIR}"/${P}-docs.patch
 	"${FILESDIR}"/${P}-stdint.patch
+	"${FILESDIR}"/${P}-fltk1.4.patch
 )
 
 DOCS=( AUTHORS.txt NEWS.txt README.adoc )