package/mesa3d-demos: needs C++

Reference:
https://gitlab.freedesktop.org/mesa/demos/-/blob/main/meson.build#L21

Fixes:
http://autobuild.buildroot.net/results/90e/90e98fa0f37462cadea0fcbff9feabad5554587d/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit c1a7079a2387738044dd76105267d6477418df48)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mesa3d-demos/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_MESA3D_DEMOS
 	bool "mesa3d-demos"
+	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_PACKAGE_HAS_LIBGL || BR2_PACKAGE_HAS_LIBGLES \
 		|| BR2_PACKAGE_HAS_LIBEGL || BR2_PACKAGE_HAS_LIBOPENVG
 	select BR2_PACKAGE_LIBGLEW if BR2_PACKAGE_XORG7 && BR2_PACKAGE_HAS_LIBGL
@@ -10,3 +11,8 @@ config BR2_PACKAGE_MESA3D_DEMOS
 	  OpenGL demos from the Mesa 3D project.
 
 	  http://mesa3d.org
+
+comment "mesa3d-demos needs a toolchain with C++"
+	depends on !BR2_INSTALL_LIBSTDCPP
+	depends on BR2_PACKAGE_HAS_LIBGL || BR2_PACKAGE_HAS_LIBGLES \
+		|| BR2_PACKAGE_HAS_LIBEGL || BR2_PACKAGE_HAS_LIBOPENVG

package/piglit/Config.in

@@ -6,7 +6,7 @@ config BR2_PACKAGE_PIGLIT
 		BR2_PACKAGE_WAFFLE_SUPPORTS_WAYLAND || \
 		BR2_PACKAGE_WAFFLE_SUPPORTS_X11_EGL || \
 		BR2_PACKAGE_WAFFLE_SUPPORTS_GBM
-	depends on BR2_INSTALL_LIBSTDCPP # python-numpy
+	depends on BR2_INSTALL_LIBSTDCPP # mesa3d-demos, python-numpy
 	depends on BR2_TOOLCHAIN_USES_GLIBC || BR2_TOOLCHAIN_USES_MUSL # python-numpy
 	select BR2_PACKAGE_LIBDRM if BR2_PACKAGE_HAS_LIBGL
 	select BR2_PACKAGE_LIBPNG