{toolchain, linux-headers}: add support for 5.18 headers

Do not add a preconfigured 5.18.x version to linux-headers as 5.18.x is
already EOL.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/linux-headers/Config.in.host

@@ -133,8 +133,12 @@ choice
 	  If your kernel headers are more recent than the latest version
 	  in the choice, then select the latest version.
 
+config BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_18
+	bool "5.18.x or later"
+	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_18
+
 config BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_17
-	bool "5.17.x or later"
+	bool "5.17.x"
 	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_17
 
 config BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_16

toolchain/Config.in

@@ -567,6 +567,10 @@ config BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_16
 config BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_17
 	bool
 	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_16
+
+config BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_18
+	bool
+	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_17
 	select BR2_TOOLCHAIN_HEADERS_LATEST
 
 # This should be selected by the latest version, above, to indicate that
@@ -580,6 +584,7 @@ config BR2_TOOLCHAIN_HEADERS_LATEST
 # stops affecting a value on the first matching default.
 config BR2_TOOLCHAIN_HEADERS_AT_LEAST
 	string
+	default "5.18" if BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_18
 	default "5.17" if BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_17
 	default "5.16" if BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_16
 	default "5.15" if BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_15

toolchain/toolchain-external/toolchain-external-custom/Config.in.options

@@ -127,8 +127,12 @@ choice
 	  If your toolchain uses headers newer than the latest version
 	  in the choice, then select the latest version.
 
+config BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_18
+	bool "5.18.x or later"
+	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_18
+
 config BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_17
-	bool "5.17.x or later"
+	bool "5.17.x"
 	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_17
 
 config BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16