linux-headers: mark EOL versions deprecated

Follow the upstream EOL cycle and mark 3.19 as deprecated for 2015.08.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/linux-headers/Config.in.host

@@ -79,6 +79,7 @@ choice
 
 	config BR2_KERNEL_HEADERS_3_19
 		bool "Linux 3.19.x kernel headers"
+		depends on BR2_DEPRECATED_SINCE_2015_08
 		select BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_19
 
 	config BR2_KERNEL_HEADERS_4_0