Build with -Drelease-safe

Debug mode is for regular development with:

	git ls-files -co --exclude-standard | entr -c -r zig build run

zig/sdl/Makefile

@@ -1,3 +1,3 @@
hello_sdl: Makefile build.zig hello_sdl.zig
	zig build
	zig build -Drelease-safe
	cp zig-out/bin/hello_sdl .