Support DESTDIR in `make install`

[ingydotnet]

Support DESTDIR in `make install`

[ingydotnet]

There is already INSTALL_LIB and INSTALL_MAN. Can you not do what you want with those?

[Benabik]

Yes, apparently I can. Thanks. This is a bigger issue with programs that store paths during build.

Still is a bit of a interface issue. With DESTDIR, I can just say "install like you normally would, just over there". Without it, I have to verify that I've set all the paths so I don't accidentally miss something. Also have to set INSTALL_LIB to $DESTDIR/(git --exec-path) and INSTALL_MAN to include the appropriate section, which is annoying.

May write up a quick patch anyway. It's a useful thing to have around for packagers.

[ingydotnet]

I'm going to close this.

I updated the docs and Makefile. make install is no longer the primary
approach. The primary way is to just modify PATH and MANPATH. This way supports
git hub upgrade. make install is still supported, but only recommended for
system installs, which is more rare I think.

I feel pretty good about these options. Do they work for you @Benabik?

I'd still welcome a patch for DESTDIR if you think it is warranted.