cmake: move CMAKE_<lang>_COMPILER_FORCED into toolchain code.

To prepare for more modular approach move the compiler forced out of
boilerplate and into the specific toolchain cmake code (generic/target).

Code is added to both generic and target toolchain modules to allow
future use of one module without requiring a load of the other module.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

cmake/app/boilerplate.cmake

@@ -477,10 +477,6 @@ if(NOT DEFINED USER_CACHE_DIR)
 endif()
 message(STATUS "Cache files will be written to: ${USER_CACHE_DIR}")
 
-# Prevent CMake from testing the toolchain
-set(CMAKE_C_COMPILER_FORCED   1)
-set(CMAKE_CXX_COMPILER_FORCED 1)
-
 include(${ZEPHYR_BASE}/cmake/verify-toolchain.cmake)
 include(${ZEPHYR_BASE}/cmake/host-tools.cmake)
 

cmake/generic_toolchain.cmake

@@ -1,5 +1,9 @@
 # SPDX-License-Identifier: Apache-2.0
 
+# Prevent CMake from testing the toolchain
+set(CMAKE_C_COMPILER_FORCED   1)
+set(CMAKE_CXX_COMPILER_FORCED 1)
+
 if(NOT TOOLCHAIN_ROOT)
   if(DEFINED ENV{TOOLCHAIN_ROOT})
     # Support for out-of-tree toolchain

cmake/target_toolchain.cmake

@@ -1,5 +1,9 @@
 # SPDX-License-Identifier: Apache-2.0
 
+# Prevent CMake from testing the toolchain
+set(CMAKE_C_COMPILER_FORCED   1)
+set(CMAKE_CXX_COMPILER_FORCED 1)
+
 # No official documentation exists for the "Generic" value, except their wiki.
 #
 # https://gitlab.kitware.com/cmake/community/wikis/doc/cmake/CrossCompiling: