package/linux-headers: drop 6.4.x option

The 6.4.x series is now EOL upstream, so drop the linux-headers option
and add legacy handling for it.

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

Config.in.legacy

@@ -146,6 +146,13 @@ endif
 
 comment "Legacy options removed in 2023.11"
 
+config BR2_KERNEL_HEADERS_6_4
+	bool "kernel headers version 6.4.x are no longer supported"
+	select BR2_LEGACY
+	help
+	  Version 6.4.x of the Linux kernel headers are no longer
+	  maintained upstream and are now removed.
+
 config BR2_PACKAGE_GOOGLE_MATERIAL_DESIGN_ICONS
 	bool "google-material-design-icons removed"
 	select BR2_LEGACY

linux/linux.hash

@@ -1,6 +1,5 @@
 # From https://www.kernel.org/pub/linux/kernel/v6.x/sha256sums.asc
 sha256  8cf10379f7df8ea731e09bff3d0827414e4b643dd41dc99d0af339669646ef95  linux-6.5.5.tar.xz
-sha256  9626ec84a39ecb009bf11a271dd520941159c165d4e62f82e3a77b79d20ff27d  linux-6.4.16.tar.xz
 sha256  a87e241ec15d53452c4efe219713a3769d88cc436b5b98cf6efb262c4aff15c0  linux-6.1.55.tar.xz
 # From https://www.kernel.org/pub/linux/kernel/v5.x/sha256sums.asc
 sha256  ef845e7934897b88e4448378ea9daacac19e07f156fe904844fab0a7d8ff5ddd  linux-5.15.133.tar.xz

package/linux-headers/Config.in.host

@@ -49,10 +49,6 @@ config BR2_KERNEL_HEADERS_6_1
 	bool "Linux 6.1.x kernel headers"
 	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_6_1
 
-config BR2_KERNEL_HEADERS_6_4
-	bool "Linux 6.4.x kernel headers"
-	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_6_4
-
 config BR2_KERNEL_HEADERS_6_5
 	bool "Linux 6.5.x kernel headers"
 	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_6_5
@@ -414,7 +410,6 @@ config BR2_DEFAULT_KERNEL_HEADERS
 	default "5.10.197"	if BR2_KERNEL_HEADERS_5_10
 	default "5.15.133"	if BR2_KERNEL_HEADERS_5_15
 	default "6.1.55"	if BR2_KERNEL_HEADERS_6_1
-	default "6.4.16"	if BR2_KERNEL_HEADERS_6_4
 	default "6.5.5"		if BR2_KERNEL_HEADERS_6_5
 	default BR2_DEFAULT_KERNEL_VERSION if BR2_KERNEL_HEADERS_VERSION
 	default "custom"	if BR2_KERNEL_HEADERS_CUSTOM_TARBALL