vala: Merge graphviz patches into one

I don't see a reason to separate the gvc-compact patch, we are actually already
maintaining our graphviz patch for a while (since openembedded-core is now simply
disabling valadoc).

pkgs/development/compilers/vala/default.nix

@@ -10,10 +10,8 @@ let
     withGraphviz ? false
   }:
   let
-    # Patches from the openembedded-core project to build vala without graphviz
-    # support. We need to apply an additional patch to allow building when the
-    # header file isn't available at all, but that patch (./gvc-compat.patch)
-    # can be shared between all versions of Vala so far.
+    # Build vala (valadoc) without graphviz support. Inspired from the openembedded-core project.
+    # https://github.com/openembedded/openembedded-core/blob/a5440d4288e09d3e/meta/recipes-devtools/vala/vala/disable-graphviz.patch
     graphvizPatch =
       {
         "0.48" = ./disable-graphviz-0.46.1.patch;
@@ -47,7 +45,7 @@ let
     # If we're disabling graphviz, apply the patches and corresponding
     # configure flag. We also need to override the path to the valac compiler
     # so that it can be used to regenerate documentation.
-    patches        = lib.optionals disableGraphviz [ graphvizPatch ./gvc-compat.patch ];
+    patches        = lib.optionals disableGraphviz [ graphvizPatch ];
     configureFlags = lib.optional  disableGraphviz "--disable-graphviz";
     # when cross-compiling ./compiler/valac is valac for host
     # so add the build vala in nativeBuildInputs

pkgs/development/compilers/vala/disable-graphviz-0.46.1.patch

@@ -259,3 +259,22 @@ index 5aa4afdea..e79b0b8f5 100644
  
  		return this;
  	}
+diff --git i/libvaladoc/Makefile.am w/libvaladoc/Makefile.am
+index 8dc398cf1..a5d8a45b4 100644
+--- i/libvaladoc/Makefile.am
++++ w/libvaladoc/Makefile.am
+@@ -176,9 +176,13 @@ endif
+ libvaladoc@PACKAGE_SUFFIX@_la_SOURCES = \
+ 	libvaladoc.vala.stamp \
+ 	$(libvaladoc_la_VALASOURCES:.vala=.c) \
+-	gvc-compat.c \
+ 	$(NULL)
+ 
++if ENABLE_GRAPHVIZ
++libvaladoc@PACKAGE_SUFFIX@_la_SOURCES += \
++	gvc-compat.c
++endif
++
+ valadoc@PACKAGE_SUFFIX@.vapi valadoc.h: libvaladoc.vala.stamp
+ libvaladoc.vala.stamp: $(libvaladoc_la_VALASOURCES)
+ 	$(VALA_V)$(VALAC) \

pkgs/development/compilers/vala/gvc-compat.patch

@@ -1,19 +0,0 @@
-diff --git i/libvaladoc/Makefile.am w/libvaladoc/Makefile.am
-index 8dc398cf1..a5d8a45b4 100644
---- i/libvaladoc/Makefile.am
-+++ w/libvaladoc/Makefile.am
-@@ -176,9 +176,13 @@ endif
- libvaladoc@PACKAGE_SUFFIX@_la_SOURCES = \
- 	libvaladoc.vala.stamp \
- 	$(libvaladoc_la_VALASOURCES:.vala=.c) \
--	gvc-compat.c \
- 	$(NULL)
- 
-+if ENABLE_GRAPHVIZ
-+libvaladoc@PACKAGE_SUFFIX@_la_SOURCES += \
-+	gvc-compat.c
-+endif
-+
- valadoc@PACKAGE_SUFFIX@.vapi valadoc.h: libvaladoc.vala.stamp
- libvaladoc.vala.stamp: $(libvaladoc_la_VALASOURCES)
- 	$(VALA_V)$(VALAC) \