kernel-headers: remove deprecated versions 3.1, 3.3, 3.5

The Linux kernel headers versions 3.1, 3.3, and 3.5 have been deprecated
since 2013.02 and thus can be removed in 2014.02.
For legacy handling, we automatically select versions 3.2, 3.4, and 3.6,
respectively.

Additionally, this patch removes the now unused symbol
BR2_DEPRECATED_SINCE_2013_02.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
diff --git a/Config.in.legacy b/Config.in.legacy
index fe91ecb..4424e31 100644
--- a/Config.in.legacy
+++ b/Config.in.legacy
@@ -119,6 +119,36 @@
 	  Due to an inexistent user base and generally poor Linux
 	  support, the support for the SH3eb architecture was removed.
 
+config BR2_KERNEL_HEADERS_3_1
+	bool "kernel headers version 3.1.x are no longer supported"
+	select BR2_KERNEL_HEADERS_3_2
+	select BR2_LEGACY
+	help
+	  Version 3.1.x of the Linux kernel headers have been deprecated
+	  for more than four buildroot releases and are now removed.
+	  As an alternative, version 3.2.x of the headers have been
+	  automatically selected in your configuration.
+
+config BR2_KERNEL_HEADERS_3_3
+	bool "kernel headers version 3.3.x are no longer supported"
+	select BR2_KERNEL_HEADERS_3_4
+	select BR2_LEGACY
+	help
+	  Version 3.3.x of the Linux kernel headers have been deprecated
+	  for more than four buildroot releases and are now removed.
+	  As an alternative, version 3.4.x of the headers have been
+	  automatically selected in your configuration.
+
+config BR2_KERNEL_HEADERS_3_5
+	bool "kernel headers version 3.5.x are no longer supported"
+	select BR2_KERNEL_HEADERS_3_6
+	select BR2_LEGACY
+	help
+	  Version 3.5.x of the Linux kernel headers have been deprecated
+	  for more than four buildroot releases and are now removed.
+	  As an alternative, version 3.6.x of the headers have been
+	  automatically selected in your configuration.
+
 config BR2_GDB_VERSION_7_2
 	bool "gdb 7.2.x is no longer supported"
 	select BR2_GDB_VERSION_7_5