package/kmsxx: needs headers >= 3.8

kms++ uses V4L2_MEMORY_DMABUF, which was only introduced in linux-3.8.

Fixes:
    http://autobuild.buildroot.org/results/8dc/8dcc74586d68195c72a58cb4944d05dd9f935fa1/
    http://autobuild.buildroot.org/results/224/22467a530a146302ef74b11f69cb5cdc54240876/
    http://autobuild.buildroot.org/results/0e5/0e576ec01bbbf68a05216f4459a8a0613c39c141/

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/kmsxx/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_KMSXX
 	bool "kms++"
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
+	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_8
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_TOOLCHAIN_HAS_THREADS # libdrm
 	select BR2_PACKAGE_LIBDRM
@@ -20,6 +21,6 @@ config BR2_PACKAGE_KMSXX_INSTALL_TESTS
 
 endif
 
-comment "kms++ needs a toolchain w/ threads, C++, gcc >= 4.8"
-        depends on !BR2_TOOLCHAIN_HAS_THREADS || !BR2_INSTALL_LIBSTDCPP || \
-		!BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
+comment "kms++ needs a toolchain w/ threads, C++, gcc >= 4.8, headers >= 3.8"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || !BR2_INSTALL_LIBSTDCPP || \
+		!BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 || !BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_8