Fix setting of cache variables

Fix for IWYU, cppcheck and clang-tidy

Author: rlalik

Diff for: tools.cmake

@@ -21,23 +21,23 @@ option(CPPCHECK "Turns on cppcheck processing if it is found." OFF)
 # as the options set.
 macro(clang_tidy)
   if(CLANG_TIDY AND CLANG_TIDY_EXE)
-    set(CMAKE_CXX_CLANG_TIDY ${CLANG_TIDY_EXE} ${ARGN})
+    set(CMAKE_CXX_CLANG_TIDY ${CLANG_TIDY_EXE} ${ARGN} CACHE STRING "" FORCE)
   endif()
 endmacro()
 
 # Adds include_what_you_use to the compilation, with the given arguments being
 # used as the options set.
 macro(include_what_you_use)
   if(IWYU AND IWYU_EXE)
-    set(CMAKE_CXX_INCLUDE_WHAT_YOU_USE ${IWYU_EXE} ${ARGN})
+    set(CMAKE_CXX_INCLUDE_WHAT_YOU_USE ${IWYU_EXE} ${ARGN} CACHE STRING "" FORCE)
   endif()
 endmacro()
 
 # Adds cppcheck to the compilation, with the given arguments being used as the
 # options set.
 macro(cppcheck)
   if(CPPCHECK AND CPPCHECK_EXE)
-    set(CMAKE_CXX_CPPCHECK ${CPPCHECK_EXE} ${ARGN})
+    set(CMAKE_CXX_CPPCHECK ${CPPCHECK_EXE} ${ARGN} CACHE STRING "" FORCE)
   endif()
 endmacro()