Make TARGET_OS and TARGET_ARCHITECTURE cached variables

Author: isuruf

CMakeLists.txt

@@ -32,8 +32,8 @@ if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
   project(Flang)
 endif()
 
-set(TARGET_OS ${CMAKE_HOST_SYSTEM_NAME})
-set(TARGET_ARCHITECTURE ${CMAKE_HOST_SYSTEM_PROCESSOR})
+set(TARGET_OS ${CMAKE_HOST_SYSTEM_NAME} CACHE STRING "Target OS")
+set(TARGET_ARCHITECTURE ${CMAKE_HOST_SYSTEM_PROCESSOR} CACHE STRING "Target Architecture")
 
 if( ${TARGET_OS} STREQUAL "Linux" )
   set(OS "LINUX")