Previously, Makefiles had to add new include paths and -D defines manually when they wanted to include RVFI.
This caused hard-to-diagnose errors in repositories consuming Toooba that expected -D RVFI to work.
This commit makes Include_RISCY_Config.mk take an optional make-variable argument RVFI, which defaults to "false", and adds the relevant paths and -D defines if it is set to "true".
This does not cover RVFI_DII, which is a simulation-only extension to allow instruction injection.
This commit also includes fixes to the Makefiles in ./builds/ to use this interface properly.