Improves the Makefile for the builder so that "all" only builds if builder.cc has been changed (really useful if using FreePSXBoot as a Git/Make submodule, so that memory card images aren't continuosly being built.
Adds a gitignore for the builder folder, so the resulting binary isn't picked as a new file, nor created memory card files
Fixes the "disableInterrupts" payload which was writing to 0x1F001074 instead to the correct 0x1F801074.
This PR: