toolchain: sdk: ib: allow external toolchain override

Allow building imagebuilder and/or sdk with dependency on the same
external toolchain as used to build the imagebuilder or sdk (so that ib
and sdk may be built using an external toolchain).

Signed-off-by: Daniel Dickinson <[email protected]>
Original patch:
https://lists.openwrt.org/pipermail/openwrt-devel/2016-January/012552.html
[rebased to current main, impvove commit title]
Signed-off-by: Pawel Dembicki <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/22089
Signed-off-by: Robert Marko <[email protected]>

target/imagebuilder/Config.in

@@ -1,6 +1,6 @@
 config IB
 	bool "Build the OpenWrt Image Builder"
-	depends on !EXTERNAL_TOOLCHAIN
+	depends on !EXTERNAL_TOOLCHAIN || EXTERNAL_TOOLCHAIN_IB
 	default BUILDBOT
 	help
 	  This is essentially a stripped-down version of the buildroot

target/sdk/Config.in

@@ -1,6 +1,6 @@
 config SDK
 	bool "Build the OpenWrt SDK"
-	depends on !EXTERNAL_TOOLCHAIN
+	depends on !EXTERNAL_TOOLCHAIN || EXTERNAL_TOOLCHAIN_SDK
 	default BUILDBOT
 	help
 	  This is essentially a stripped-down version of the buildroot

toolchain/Config.in

@@ -194,6 +194,22 @@ menuconfig EXTERNAL_TOOLCHAIN
 		  Specify additional directories searched for libraries (override LDFLAGS).
 		  Use ./DIR for directories relative to the root above.
 
+	config EXTERNAL_TOOLCHAIN_IB
+		bool
+		prompt "Allow Imagebuilder with external toolchain" if DEVEL
+		depends on EXTERNAL_TOOLCHAIN
+		default n
+		help
+		  Allows selecting to build ImageBuilder even with external toolchain.
+
+	config EXTERNAL_TOOLCHAIN_SDK
+		bool
+		prompt "Allow SDK with external toolchain" if DEVEL
+		depends on EXTERNAL_TOOLCHAIN
+		default n
+		help
+		  Allows selecting to build SDK even with external toolchain.
+
 config NEED_TOOLCHAIN
 	bool
 	depends on DEVEL