disable the compile-flags-changed check

Is there any way to disable the "the compile flags have changed,
recompile everything" check?  I want to built with another prefix than
installing to create a tarball I copy to other machines.  Is there any
way to do this?  Otherwise: could we include something like this?

ifeq ($(IGNORE_CFLAG_CHANGES),)
# old GIT-CFLAGS rules
else
GIT-CFLAGS:
        touch "$@"
endif