Respect Parent Project's use of CMAKE_RUNTIME_OUTPUT_DIRECTORY

[jwillikers]

The use of CMAKE_RUNTIME_OUTPUT_DIRECTORY in the CMakeLists.txt file does not allow parent projects to override it.
Would it be possible to only set that variable if it is not already set?
The CMake code to accomplish follows below.

if(NOT CMAKE_RUNTIME_OUTPUT_DIRECTORY)
  set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
endif()

[jwillikers]

You might also want to use GNUInstallDirs.

if(NOT CMAKE_RUNTIME_OUTPUT_DIRECTORY)
  include(GNUInstallDirs)
  set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR})
endif()

[vitaut]

Would it be possible to only set that variable if it is not already set?

Sure, a PR is welcome.

You might also want to use GNUInstallDirs.

I suggest keeping bin for simplicity.

[jwillikers]

I'll get a PR ready.