README.md: Remove include flag for Linux-to-Windows cross-compiling as it's already defined

Signed-off-by: Lilis Iskandar <[email protected]>

Author: veeableful

README.md

@@ -113,7 +113,7 @@ Cross-compiling
 2. Download the SDL2 development package for MinGW [here](http://libsdl.org/download-2.0.php).
 3. Extract the SDL2 development package and copy the `x86_64-w64-mingw32` folder inside recursively to the system's MinGW `x86_64-w64-mingw32` folder. You may also do the same for the `i686-w64-mingw32` folder.
    * On **Arch Linux**, it's `cp -r x86_64-w64-mingw32 /usr`.
-4. Now you can start cross-compiling your Go program by running `env CGO_ENABLED="1" CC="/usr/bin/x86_64-w64-mingw32-gcc" GOOS="windows" CGO_LDFLAGS="-lmingw32 -lSDL2" CGO_CFLAGS="-I/usr/x86_64-w64-mingw32/include/SDL2 -D_REENTRANT" go build -x main.go`. You can change some of the parameters if you'd like to. In this example, it should produce a `main.exe` executable file.
+4. Now you can start cross-compiling your Go program by running `env CGO_ENABLED="1" CC="/usr/bin/x86_64-w64-mingw32-gcc" GOOS="windows" CGO_LDFLAGS="-lmingw32 -lSDL2" CGO_CFLAGS="-D_REENTRANT" go build -x main.go`. You can change some of the parameters if you'd like to. In this example, it should produce a `main.exe` executable file.
 5. Before running the program, you need to put `SDL2.dll` from the [SDL2 runtime package](http://libsdl.org/download-2.0.php) for Windows in the same folder as your executable.
 6. Now you should be able to run the program using Wine or Windows!