package/x11r7/libepoxy: fix OpenGL / EGL dependencies

libepoxy depends on egl, opengl is an optional dependency

Fixes
http://autobuild.buildroot.net/results/f7e/f7e6a42f53cb4ca523d2eeefde85c44770f6011e
http://autobuild.buildroot.net/results/025/025a3d3b4d3dd4f496dcbf09f2dd279116250207

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/x11r7/libepoxy/Config.in

@@ -1,7 +1,13 @@
 config BR2_PACKAGE_LIBEPOXY
 	bool "epoxy"
-	depends on BR2_PACKAGE_MESA3D
+	select BR2_PACKAGE_XLIB_LIBX11
+	select BR2_PACKAGE_XUTIL_UTIL_MACROS
+	depends on BR2_PACKAGE_HAS_LIBEGL
 	help
-	  Epoxy is a library for handling OpenGL function pointer management for you.
+	  Epoxy is a library for handling OpenGL function pointer
+	  management for you.
 
 	  https://github.com/anholt/libepoxy
+
+comment "epoxy needs an OpenGL EGL backend"
+	depends on !BR2_PACKAGE_HAS_LIBEGL

package/x11r7/libepoxy/libepoxy.mk

@@ -8,8 +8,13 @@ LIBEPOXY_VERSION = v1.2
 LIBEPOXY_SITE = $(call github,anholt,libepoxy,$(LIBEPOXY_VERSION))
 LIBEPOXY_INSTALL_STAGING = YES
 LIBEPOXY_AUTORECONF = YES
-LIBEPOXY_DEPENDENCIES = mesa3d
+LIBEPOXY_DEPENDENCIES = xlib_libX11 xutil_util-macros libegl \
+	$(if $(BR2_PACKAGE_HAS_LIBGL),libgl)
 LIBEPOXY_LICENSE = MIT
 LIBEPOXY_LICENSE_FILES = COPYING
 
+# needed for rpi-userland
+LIBEPOXY_CFLAGS += `$(PKG_CONFIG_HOST_BINARY) --cflags egl`
+LIBEPOXY_CONF_ENV += CFLAGS="$(TARGET_CFLAGS) $(LIBEPOXY_CFLAGS)"
+
 $(eval $(autotools-package))