* Remove the usage of global flags and definitions
set through the CMAKE_CXX_FLAGS variable.
* Use cmake target compile features for setting the
CXX standard automatically.
* Make C++14 globally available in the project
* Closes#21033
(cherry picked from commit e60c1f84a7)
-Wwrite-strings is default enabled when -Wall is set in clang/gcc, hence removed.
-Woverloaded-virtual is now enabled for C++-code only, this removes the useless warnings when dabbling with C-only code.