Don't pollute global includes/defines namespace

A function like add_definitions() adds definitions to ALL targets, not
just VVVVVV. This kind of namespace pollution is messy, and could result
in bugs if you pollute with the right kind of pollutant.

So instead of using add_definitions(), use target_compile_definitions().
And instead of using include_directories(), use
target_include_directories().

desktop_version/CMakeLists.txt

@@ -24,10 +24,6 @@ if(OFFICIAL_BUILD AND NOT MAKEANDPLAY)
 	set(GOG ON)
 endif()
 
-if(MAKEANDPLAY)
-	add_definitions(-DMAKEANDPLAY)
-endif()
-
 if(${CMAKE_VERSION} VERSION_LESS "3.1.3")
 	message(WARNING "Your CMake version is too old; set -std=c90 -std=c++98 yourself!")
 else()
@@ -60,9 +56,6 @@ if(APPLE)
 	message(STATUS "Using macOS SDK at ${CMAKE_OSX_SYSROOT}")
 endif()
 
-# Compiler Flags
-add_definitions(-DPHYSFS_SUPPORTS_DEFAULT=0 -DPHYSFS_SUPPORTS_ZIP=1)
-
 # RPATH
 if(NOT WIN32)
 	if(APPLE)
@@ -81,22 +74,6 @@ if(NOT WIN32)
 	set(CMAKE_INSTALL_RPATH_USE_LINK_PATH FALSE)
 endif()
 
-# Include Directories
-if(BUNDLE_DEPENDENCIES)
-	include_directories(
-		src
-		../third_party/tinyxml2
-		../third_party/physfs
-		../third_party/lodepng
-		../third_party/utfcpp/source
-	)
-else()
-	include_directories(
-		src
-		../third_party/lodepng
-	)
-endif()
-
 # Source Lists
 set(VVV_SRC
 	src/BinaryBlob.cpp
@@ -140,11 +117,45 @@ if(NOT CUSTOM_LEVEL_SUPPORT STREQUAL "DISABLED")
 endif()
 if(STEAM)
 	list(APPEND VVV_SRC src/SteamNetwork.c)
-	add_definitions(-DSTEAM_NETWORK)
 endif()
 if(GOG)
 	list(APPEND VVV_SRC src/GOGNetwork.c)
-	add_definitions(-DGOG_NETWORK)
+endif()
+
+# Executable information
+if(WIN32)
+	add_executable(VVVVVV WIN32 ${VVV_SRC})
+else()
+	add_executable(VVVVVV ${VVV_SRC})
+endif()
+
+# Include Directories
+if(BUNDLE_DEPENDENCIES)
+	target_include_directories(
+		VVVVVV PRIVATE
+		src
+		../third_party/tinyxml2
+		../third_party/physfs
+		../third_party/lodepng
+		../third_party/utfcpp/source
+	)
+else()
+	target_include_directories(
+		VVVVVV PRIVATE
+		src
+		../third_party/lodepng
+	)
+endif()
+
+if(MAKEANDPLAY)
+	target_compile_definitions(VVVVVV PRIVATE -DMAKEANDPLAY)
+endif()
+
+if(STEAM)
+	target_compile_definitions(VVVVVV PRIVATE -DSTEAM_NETWORK)
+endif()
+if(GOG)
+	target_compile_definitions(VVVVVV PRIVATE -DGOG_NETWORK)
 endif()
 
 set(XML2_SRC
@@ -168,13 +179,6 @@ if(APPLE)
 endif()
 set(PNG_SRC ../third_party/lodepng/lodepng.c)
 
-# Executable information
-if(WIN32)
-	add_executable(VVVVVV WIN32 ${VVV_SRC})
-else()
-	add_executable(VVVVVV ${VVV_SRC})
-endif()
-
 if(NOT OFFICIAL_BUILD)
 	# Add interim commit hash and its date to the build
 
@@ -258,6 +262,9 @@ target_compile_definitions(lodepng-static PRIVATE
 if(BUNDLE_DEPENDENCIES)
 	add_library(tinyxml2-static STATIC ${XML2_SRC})
 	add_library(physfs-static STATIC ${PFS_SRC} ${PFSP_SRC})
+	target_compile_definitions(physfs-static PRIVATE
+		-DPHYSFS_SUPPORTS_DEFAULT=0 -DPHYSFS_SUPPORTS_ZIP=1
+	)
 
 	# PhysFS needs some extensions...
 	if(${CMAKE_VERSION} VERSION_GREATER "3.1.3"