Added install target to Makefile

[jaylogue]

@jbglaw : Here's an install target for you. If this looks good let me know and I will merge the change.

[jbglaw]

Works perfectly: http://toolchain.lug-owl.de/laminar/jobs/retrofuse/15

jbglaw@lili:~$ tar tzvf /var/cache/laminar/retrofuse-dd0656fa62c6a4bbe1c82d60612e5a27229be128.tar.gz
drwxr-xr-x foo/foo           0 2023-08-21 08:23 _inst_/
drwxr-xr-x foo/foo           0 2023-08-21 08:23 _inst_/bin/
drwxr-xr-x foo/foo           0 2023-08-21 08:23 _inst_/bin/bin/
-rwxr-xr-x foo/foo       64248 2023-08-21 08:20 _inst_/bin/bin/v7fs
-rwxr-xr-x foo/foo       68424 2023-08-21 08:20 _inst_/bin/bin/bsd29fs
-rwxr-xr-x foo/foo       88944 2023-08-21 08:20 _inst_/bin/bin/bsd211fs
-rwxr-xr-x foo/foo       60152 2023-08-21 08:20 _inst_/bin/bin/v6fs

[jaylogue]

Great! Thanks for testing this.

BTW, was the double "bin" directories intentional? (_inst_/bin/bin/...)

[jbglaw]

Good catch! ...but actually, the answer is kind-of "Yes!" My invocation (see the logging helper log_execute call right above the referenced build log) had prefix=/bin instead of prefix=/usr set, so it was a typo on my side and subsequently correctly handled within the new Makefile target.

[jbglaw]

New CI build (now from master instead of the feature/install branch) here: http://toolchain.lug-owl.de/laminar/jobs/retrofuse/17

Thanks!