[CMake] fix generated headers location, fix #14

CMakeLists.txt

@@ -24,6 +24,7 @@ IF(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
   SET_PROPERTY(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "Debug" "Release" "MinSizeRel" "RelWithDebInfo")
 ENDIF()
 
+SET(CUSTOM_HEADER_DIR ${PROJECT_NAME})
 
 CMAKE_POLICY(SET CMP0048 NEW)
 PROJECT(${PROJECT_NAME} VERSION ${PROJECT_VERSION_FULL} LANGUAGES CXX)