GNUmakefile: add install target for linux systems

[leongross]

Small PR adding the option to quickly install custom build binaries to the system path, similar to the way the docs describe it. There are 2 options: local and system-wide installation. The default is system-wide installation.

# defaults to system installation
make install

# system installation, INSTALL_SYSTEM_DIR defaults to /usr/bin
INSTALL_SYSTEM_DIR=<customDir> make install

# user installation, INSTALL_LOCAL_DIR defaults to $HOME/go/bin
INSTALL_LOCAL=1 INSTALL_LOCAL_DIR=<customDir> make install

[aykevl]

Is there a reason you want to put it in a system path, and not effectively run go install (that puts it in $GOBIN)? Putting it in $GOBIN would make much more sense to me (and in fact, I'd use that a lot if it were available).

[leongross]

On a multi-user system, it might be useful to install the binary on a system path.
Especially when uninstalling the tinygo package from the system path via the systems package manager for development purposes.
But the local installation should be replaced by a go install. I still think it is a good idea to wrap this into a make install, since all the rest of the build system is also wrapped into that so it would just make sense.

[leongross]

@dkegel-fastly I saw you have been working on the GNUmakefile, thoughts on this PR?

[dkegel-fastly]

Have you considered providing the old-school standard variables and targets that packagers rely on and experienced "make" users expect?

In particular, I think autoconf-generated configure scripts let users control installation location in two ways

make install prefix=/alternate/directory
make install DESTDIR=/alternate/directory

If I understand correctly, both are needed because the first method works on windows (as it replaces the whole directory including drive letter), and the second is expected by e.g. dh_auto_install, but they might have identical effect for us.

Debian packagers would thank you :-)

See https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.72/html_node/Installation-Names.html
and e.g. https://manpages.debian.org/testing/debhelper/dh_auto_install.1.en.html

[dankegel]

Gosh darn it, now I remember: GNUmakefile is only for the static build. "Make install" should copy build/TinyGo, not do "go install". Glad you got that right.

Also, using profile and DESTDIR must stack; DESTDIR applies after profile. (It is for package wranglers only.)

[leongross]

Thanks @dkegel-fastly for the feedback. I should really adapt this patch to the convention utilizing prefix and DESTDIR.

[dkegel-fastly]

also fix the typos in the comments else the dreaded Spelling Police will come after you :-)