Release for RPi; build info

[vogler]

I have gtm setup via brew on macOS and linuxbrew on WSL, but I can't install it on my Raspberry Pis (RPi3 with 32bit kernel, RPi4 with 64bit kernel).
Both the linxubrew version as well as gtm.v1.3.5.linux.tar.gz complain with zsh: exec format error: gtm. I exptected linuxbrew to install a 32-bit ARM binary, but it didn't:

$  file /home/linuxbrew/.linuxbrew/Cellar/gtm/v1.3.5/bin/gtm
/home/linuxbrew/.linuxbrew/Cellar/gtm/v1.3.5/bin/gtm: ELF 64-bit LSB executable, x86-6
4, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for
GNU/Linux 2.6.24, Go BuildID=z9f84jkjRU95gO0cl2dx/xhTQdzqsygoL2999uRVL/S1xJG3BRObu_Hbm
IQv_w/D4htBoMCCH6Zr1dH3jLj, BuildID[sha1]=5a73657f9fd81cc90c51ceea87cbe0aa1ec68a0a, wi
th debug_info, not stripped

$ file gtm # from gtm.v1.3.5.linux.tar.gz
gtm: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpre
ter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.24, Go BuildID=z9f84jkjRU95gO0cl2dx
/xhTQdzqsygoL2999uRVL/S1xJG3BRObu_HbmIQv_w/D4htBoMCCH6Zr1dH3jLj, BuildID[sha1]=5a73657
f9fd81cc90c51ceea87cbe0aa1ec68a0a, with debug_info, not stripped

I then tried to build it myself, which also failed:

$  make git2go
$  go get -d ./... # no idea about go, taken from .travis.yml
$ make
go build --tags 'static' -ldflags "-X main.Version=0.0.0-dev-019de99" -o bin/gtm
# github.com/libgit2/git2go
../.go/src/github.com/libgit2/git2go/diff.go:441:2: constant 2147483648 overflows DiffOptionsFlag
make: *** [Makefile:13: build] Error 2