Homebrew installs to a different directory on macOS/arm64.
this adds checks in the Makefile and in kristall.pro, and sets
the correct paths to Homebrew depending on whether the build is
targeting arm64 or not.
Currently we install the man page by default to /usr/share/man/man1/kristall.1. This should be fine - we allow users to specify the MANPATH variable on command line if they wish to install somewhere else. We could make it more complicated by using /usr/share/man:/usr/lib/jvm/default/man command to determine install location, but unless this becomes an issue, I don't think we'd need to use that
This broke running make with flags like -k or -s set,
because make apparently removes hyphens from those flags,
making it to think that we want to run a not existing target.
Also, flags are stored in env, so child processes know which flags
are in use and we don't have to provide them again.
This causes install to create directories in the install path if they
do not already exist.
mkdir -p doesn't work here if prefix directories don't exist yet.
Monitoring the modified state of source files for the build task means
that simply running 'make' will detect if a rebuild is actually needed
or not. Currently if the build file exists make is not run again. A
clean must be run first, then make. This is an improvement on that.
quietok(david)