ENH: merge CMake-CrossCompileBasic to HEAD

-add a RESULT_VARIABLE to INCLUDE()
-add CMAKE_TOOLCHAIN_FILE for specifiying your (potentially crosscompiling) toolchain
-have TRY_RUN() complain if you try to use it in crosscompiling mode (which were compiled but cannot run on this system)
-use CMAKE_EXECUTABLE_SUFFIX in TRY_RUN(), probably TRY_RUN won't be able to
run the executables if they have a different suffix because they are
probably crosscompiled, but nevertheless it should be able to find them
-make several cmake variables presettable by the user: CMAKE_C/CXX_COMPILER, CMAKE_C/CXX_OUTPUT_EXTENSION, CMAKE_SYSTEM_NAME, CMAKE_SYSTEM_INFO_FILE
-support prefix for GNU toolchains (arm-elf-gcc, arm-elf-ar, arm-elf-strip etc.)
-move ranlib on OSX from the file command to a command in executed in cmake_install.cmake
-add support for stripping during install in cmake_install.cmake
-split out cl.cmake from Windows-cl.cmake, first (very incomplete) step to support MS crosscompiling tools
-remove stdio.h from the simple C program which checks if the compiler works, since this may not exist for some embedded platforms
-create a new CMakeFindBinUtils.cmake which collects the search fro ar, ranlib, strip, ld, link, install_name_tool and other tools like these
-add support for CMAKE_FIND_ROOT_PATH for all FIND_XXX commands, which is a
list of directories which will be prepended to all search directories, right
now as a cmake variable, turning it into a global cmake property may need
some more work
-remove cmTestTestHandler::TryExecutable(), it's unused
-split cmFileCommand::HandleInstall() into slightly smaller functions

Alex

Modules/CMakeDetermineSystem.cmake

@@ -25,37 +25,60 @@
 # Ultrix                        ULTRIX  
 # cygwin                        CYGWIN_NT-5.1
 # MacOSX                        Darwin
-IF(UNIX)
-  FIND_PROGRAM(CMAKE_UNAME uname /bin /usr/bin /usr/local/bin )
-  IF(CMAKE_UNAME)
-    EXEC_PROGRAM(uname ARGS -s OUTPUT_VARIABLE CMAKE_SYSTEM_NAME)
-    EXEC_PROGRAM(uname ARGS -r OUTPUT_VARIABLE CMAKE_SYSTEM_VERSION)
-    IF(CMAKE_SYSTEM_NAME MATCHES "Linux")
-      EXEC_PROGRAM(uname ARGS -m OUTPUT_VARIABLE CMAKE_SYSTEM_PROCESSOR
-        RETURN_VALUE val)
-    ELSE(CMAKE_SYSTEM_NAME MATCHES "Linux")
-      EXEC_PROGRAM(uname ARGS -p OUTPUT_VARIABLE CMAKE_SYSTEM_PROCESSOR
-        RETURN_VALUE val)
-      IF("${val}" GREATER 0)
+
+IF(CMAKE_TOOLCHAIN_FILE)
+  # at first try to load it as path relative to the directory from which cmake has been run
+  INCLUDE("${CMAKE_BINARY_DIR}/${CMAKE_TOOLCHAIN_FILE}" OPTIONAL RESULT_VARIABLE _INCLUDED_TOOLCHAIN_FILE)
+  IF(NOT _INCLUDED_TOOLCHAIN_FILE)
+     # if the file isn't found there, check the default locations
+     INCLUDE("${CMAKE_TOOLCHAIN_FILE}" OPTIONAL RESULT_VARIABLE _INCLUDED_TOOLCHAIN_FILE)
+  ENDIF(NOT _INCLUDED_TOOLCHAIN_FILE)
+
+  IF(_INCLUDED_TOOLCHAIN_FILE)
+    SET(CMAKE_TOOLCHAIN_FILE "${_INCLUDED_TOOLCHAIN_FILE}")
+  ELSE(_INCLUDED_TOOLCHAIN_FILE)
+    MESSAGE(FATAL_ERROR "Could not find toolchain file: ${CMAKE_TOOLCHAIN_FILE}") 
+  ENDIF(_INCLUDED_TOOLCHAIN_FILE)
+
+  IF(NOT DEFINED CMAKE_CROSSCOMPILING)
+    SET(CMAKE_CROSSCOMPILING TRUE)
+  ENDIF(NOT DEFINED CMAKE_CROSSCOMPILING)
+ENDIF(CMAKE_TOOLCHAIN_FILE)
+
+IF(NOT CMAKE_SYSTEM_NAME)
+  IF(UNIX)
+    FIND_PROGRAM(CMAKE_UNAME uname /bin /usr/bin /usr/local/bin )
+    IF(CMAKE_UNAME)
+      EXEC_PROGRAM(uname ARGS -s OUTPUT_VARIABLE CMAKE_SYSTEM_NAME)
+      EXEC_PROGRAM(uname ARGS -r OUTPUT_VARIABLE CMAKE_SYSTEM_VERSION)
+      IF(CMAKE_SYSTEM_NAME MATCHES "Linux")
         EXEC_PROGRAM(uname ARGS -m OUTPUT_VARIABLE CMAKE_SYSTEM_PROCESSOR
           RETURN_VALUE val)
+      ELSE(CMAKE_SYSTEM_NAME MATCHES "Linux")
+        EXEC_PROGRAM(uname ARGS -p OUTPUT_VARIABLE CMAKE_SYSTEM_PROCESSOR
+          RETURN_VALUE val)
+        IF("${val}" GREATER 0)
+          EXEC_PROGRAM(uname ARGS -m OUTPUT_VARIABLE CMAKE_SYSTEM_PROCESSOR
+            RETURN_VALUE val)
+        ENDIF("${val}" GREATER 0)
+      ENDIF(CMAKE_SYSTEM_NAME MATCHES "Linux")
+      # check the return of the last uname -m or -p 
+      IF("${val}" GREATER 0)
+          SET(CMAKE_SYSTEM_PROCESSOR "unknown")
       ENDIF("${val}" GREATER 0)
-    ENDIF(CMAKE_SYSTEM_NAME MATCHES "Linux")
-    # check the return of the last uname -m or -p 
-    IF("${val}" GREATER 0)
-        SET(CMAKE_SYSTEM_PROCESSOR "unknown")
-    ENDIF("${val}" GREATER 0)
-    SET(CMAKE_UNAME ${CMAKE_UNAME} CACHE INTERNAL "uname command")
-    # processor may have double quote in the name, and that needs to be removed
-    STRING(REGEX REPLACE "\"" "" CMAKE_SYSTEM_PROCESSOR "${CMAKE_SYSTEM_PROCESSOR}")
-    STRING(REGEX REPLACE "/" "_" CMAKE_SYSTEM_PROCESSOR "${CMAKE_SYSTEM_PROCESSOR}")
-  ENDIF(CMAKE_UNAME)
-ELSE(UNIX)
-  IF(WIN32)
-    SET (CMAKE_SYSTEM_NAME "Windows")
-    SET (CMAKE_SYSTEM_PROCESSOR "$ENV{PROCESSOR_ARCHITECTURE}")
-  ENDIF(WIN32)
-ENDIF(UNIX)
+      SET(CMAKE_UNAME ${CMAKE_UNAME} CACHE INTERNAL "uname command")
+      # processor may have double quote in the name, and that needs to be removed
+      STRING(REGEX REPLACE "\"" "" CMAKE_SYSTEM_PROCESSOR "${CMAKE_SYSTEM_PROCESSOR}")
+      STRING(REGEX REPLACE "/" "_" CMAKE_SYSTEM_PROCESSOR "${CMAKE_SYSTEM_PROCESSOR}")
+    ENDIF(CMAKE_UNAME)
+  ELSE(UNIX)
+    IF(WIN32)
+      SET (CMAKE_SYSTEM_NAME "Windows")
+      SET (CMAKE_SYSTEM_PROCESSOR "$ENV{PROCESSOR_ARCHITECTURE}")
+    ENDIF(WIN32)
+  ENDIF(UNIX)
+ENDIF(NOT CMAKE_SYSTEM_NAME)
+
 
 IF(NOT CMAKE_SYSTEM_NAME)
   SET(CMAKE_SYSTEM_NAME "UnknownOS")