Makefile: detect new Homebrew location for ARM-based Macs
With the introduction of the ARM-based Macs the default location for
Homebrew has changed from "/usr/local" to "/opt/homebrew". We only
handle the former location though, which means that unless the user has
manually configured required search paths we won't be able to locate it.
Improve upon this by adding relevant paths to our CFLAGS and LDFLAGS as
well as detecting the location of msgfmt(1).
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>