Define the `DEBUG` macro in CMakeLists.txt

Fixes #334

CMakeLists.txt

@@ -17,8 +17,8 @@ include(GNUInstallDirs)
 ################################
 # set lib version here
 
-set(GENERIC_LIB_VERSION "3.0.0")
-set(GENERIC_LIB_SOVERSION "3")
+set(GENERIC_LIB_VERSION "3.0.0")
+set(GENERIC_LIB_SOVERSION "3")
 
 
 ################################
@@ -51,6 +51,8 @@ if(MSVC)
 	add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif(MSVC)
 
+set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DDEBUG")
+
 ################################
 # Add targets
 option(BUILD_SHARED_LIBS "build shared or static libraries" ON)