package/mesa3d: always pass --with-platforms

If --with-platforms is not used mesa3d defaults to x11:
https://cgit.freedesktop.org/mesa/mesa/tree/configure.ac?h=17.1#n1641
https://cgit.freedesktop.org/mesa/mesa/tree/configure.ac?h=17.1#n1659

This will break configure when x11 is not needed because the defconfig
has no mesa3d drivers enabled. To solve the problem we always pass
--with-platforms, even with empty values and also for non-egl builds.

Fixes
http://autobuild.buildroot.net/results/d16/d16b39d16b5bee5c09b1e996941a275a4337c3c1/

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

package/mesa3d/mesa3d.mk

@@ -141,8 +141,6 @@ endef
 MESA3D_POST_INSTALL_STAGING_HOOKS += MESA3D_REMOVE_OPENGL_HEADERS
 endif
 
-ifeq ($(BR2_PACKAGE_MESA3D_OPENGL_EGL),y)
-MESA3D_PROVIDES += libegl
 ifeq ($(BR2_PACKAGE_MESA3D_DRI_DRIVER),y)
 MESA3D_PLATFORMS = drm
 else ifeq ($(BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_VC4),y)
@@ -159,10 +157,15 @@ endif
 ifeq ($(BR2_PACKAGE_XORG7),y)
 MESA3D_PLATFORMS += x11
 endif
+
+MESA3D_CONF_OPTS += \
+	--with-platforms=$(subst $(space),$(comma),$(MESA3D_PLATFORMS))
+
+ifeq ($(BR2_PACKAGE_MESA3D_OPENGL_EGL),y)
+MESA3D_PROVIDES += libegl
 MESA3D_CONF_OPTS += \
 	--enable-gbm \
-	--enable-egl \
-	--with-egl-platforms=$(subst $(space),$(comma),$(MESA3D_PLATFORMS))
+	--enable-egl
 else
 MESA3D_CONF_OPTS += \
 	--disable-egl