Change default prefix location for linux.

[FredericGuilbault]

This issue open the convo around the Pull Request #47

The original issue raised was about changing the default install location in the makefile.

The correct install location for handbuild binaries under linux (And probably OSX) should be /usr/local/bin/

For reference:
The linux FHS standards says:

Purpose of The /usr/local hierarchy is for use by the system administrator when installing software locally. It needs to be safe from being overwritten when the system software is updated. It may be used for programs and data that are shareable amongst a group of hosts, but not found in /usr.
Locally  installed  software  must  be  placed  within  /usr/local  rather  than  /usr  unless  it  is  being installed to replace or upgrade software in /usr.

https://refspecs.linuxfoundation.org/FHS_3.0/fhs-3.0.pdf (page 21)

Also Unix standards says :

/usr/local | Resembles /usr in structure, but its subdirectories are  used for additions not part of the operating system distribution, such  as custom programs or files from a BSD Ports collection. Usually has subdirectories such as /usr/local/lib or /usr/local/bin.

https://en.wikipedia.org/wiki/Unix_filesystem#Conventional_directory_layout

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This said, the challenge now is to figure all the implications and changes required.

[FredericGuilbault]

I made a quick review:

Last comment here, suggest editing the service file withing the make file to make sure they both are coherent in all case.
https://bbs.archlinux.org/viewtopic.php?id=214576

Here, they suggest to hardcode some $PATH variable. and this could support both path.
https://askubuntu.com/questions/1014480/how-do-i-add-bin-to-path-for-a-systemd-service