move SDL2 to depends in the src dir

.gitignore

@@ -1,7 +1,7 @@
 # linux backup files
 *~
 
-#Kdevelop project files
+# Kdevelop project files
 *.kdev4
 .kdev4
 
@@ -70,7 +70,7 @@ tags
 # Mac OS X .DS_Store files
 .DS_Store
 
-#VS is annoying about this one.
+# VS is annoying about this one.
 /build/win64/DF_PATH.txt
 /build/win32/DF_PATH.txt
 /.vs
@@ -81,5 +81,6 @@ tags
 # external plugins
 /plugins/CMakeLists.custom.txt
 
-# steam api
+# 3rd party downloads
 depends/steam
+depends/SDL2

CMakeLists.txt

@@ -293,12 +293,13 @@ find_package(ZLIB REQUIRED)
 include_directories(${ZLIB_INCLUDE_DIRS})
 
 # Download SDL release and extract into depends in the build dir
-# all we need are the header files, so the same release package will work for all platforms
+# all we need are the header files (including generated headers), so the same release package
+# will work for all platforms
 # (the above statement is untested for OSX)
 set(SDL_VERSION 2.26.2)
 set(SDL_ZIP_MD5 574daf26d48de753d0b1e19823c9d8bb)
 set(SDL_ZIP_FILE SDL2-devel-${SDL_VERSION}-VC.zip)
-set(SDL_ZIP_PATH ${CMAKE_BINARY_DIR}/depends/SDL2/)
+set(SDL_ZIP_PATH ${dfhack_SOURCE_DIR}/depends/SDL2/)
 download_file("https://github.com/libsdl-org/SDL/releases/download/release-${SDL_VERSION}/${SDL_ZIP_FILE}"
     ${SDL_ZIP_PATH}${SDL_ZIP_FILE}
     ${SDL_ZIP_MD5})