RPi: add clang & clang-check support

cmake/toolchains/Toolchain-arm-linux-clang-gnueabihf-raspbian.cmake

@@ -0,0 +1,69 @@
+include(CMakeForceCompiler)
+
+if ($ENV{RPI_TOOLCHAIN_DIR} STREQUAL "")
+        message(FATAL_ERROR "RPI_TOOLCHAIN_DIR not set")
+else()
+        set(RPI_TOOLCHAIN_DIR $ENV{RPI_TOOLCHAIN_DIR})
+endif()
+
+# this one is important
+set(CMAKE_SYSTEM_NAME Generic)
+
+#this one not so much
+set(CMAKE_SYSTEM_VERSION 1)
+
+# specify the cross compiler
+# requires a symbolic link typically from /usr/bin/clang
+find_program(C_COMPILER clang
+	PATHS ${RPI_TOOLCHAIN_DIR}/gcc-linaro-arm-linux-gnueabihf-raspbian/bin
+	NO_DEFAULT_PATH
+	)
+
+if(NOT C_COMPILER)
+	message(FATAL_ERROR "could not find C compiler")
+endif()
+cmake_force_c_compiler(${C_COMPILER} Clang)
+
+find_program(CXX_COMPILER clang++
+	PATHS ${RPI_TOOLCHAIN_DIR}/gcc-linaro-arm-linux-gnueabihf-raspbian/bin
+	NO_DEFAULT_PATH
+	)
+
+if(NOT CXX_COMPILER)
+	message(FATAL_ERROR "could not find C++ compiler")
+endif()
+cmake_force_cxx_compiler(${CXX_COMPILER} Clang)
+
+# compiler tools
+foreach(tool objcopy nm ld)
+	string(TOUPPER ${tool} TOOL)
+	find_program(${TOOL} arm-linux-gnueabihf-${tool}
+		PATHS ${RPI_TOOLCHAIN_DIR}/gcc-linaro-arm-linux-gnueabihf-raspbian/bin
+		NO_DEFAULT_PATH
+		)
+	if(NOT ${TOOL})
+		message(FATAL_ERROR "could not find arm-linux-gnueabihf-${tool}")
+	endif()
+endforeach()
+
+# os tools
+foreach(tool echo grep rm mkdir nm cp touch make unzip)
+	string(TOUPPER ${tool} TOOL)
+	find_program(${TOOL} ${tool})
+	if(NOT ${TOOL})
+		message(FATAL_ERROR "could not find ${TOOL}")
+	endif()
+endforeach()
+
+add_definitions(
+	-D __RPI
+	)
+
+# where is the target environment
+set(CMAKE_FIND_ROOT_PATH  get_file_component(${C_COMPILER} PATH))
+
+# search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+# for libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)