Makefile: fix/change macro behaviour

- fix incorrect $(CFLAGS) usage
- use -O0 optimization by default in CFLAGS
- suggest DEFINE for preprocessor macro definitions

change how the _PATH_ETC macro behaves

- stop overriding _PATH_ETC if defined via cmdline
  (allow setting e.g. -D_PATH_ETC=\\\"/home/$(USER)/bin\\\" in CFLAGS)
- if _PATH_ETC is not defined, default to "/etc/randrd"

randrd.c: remove build instructions

.gitignore: add the default binary name

make randrd.c compile on Linux

add a Makefile; add a .gitignore

Remember outputs, so we don't emit events twice; Add pledge(2), unveil(2)

Initial commit