macOS: fix CMake Xcode generator.

This is done by setting `CMAKE_RUNTIME_OUTPUT_DIRECTORY` to `$<1:${CMAKE_BINARY_DIR}/bin>`

CMakeLists.txt

@@ -49,6 +49,9 @@ set(OPENGL 3 CACHE STRING "OpenGL version to use (one of: 1 3)")
 
 set(EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR}/bin)
 set(LIBRARY_OUTPUT_PATH    ${CMAKE_BINARY_DIR}/bin)
+if("${CMAKE_GENERATOR}" STREQUAL "Xcode")
+    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY $<1:${CMAKE_BINARY_DIR}/bin>)
+endif()
 
 if(NOT CMAKE_C_COMPILER_ID STREQUAL CMAKE_CXX_COMPILER_ID)
     message(FATAL_ERROR "C and C++ compilers should be supplied by the same vendor")