Suggestion on enhancing installation-related parameter values

[QubitPi]

On linux, if we default PREFIX to /usr/local in Makefile.base, then user can invoke all MDBM command-line tools anywhere right after make install. Whereas if we use PREFIX ?= /tmp/install, auto-complete command using tab is not working.

A Troubleshooting section is added to README.build to make it easier for user to install MDBM.

[hawk259]

Can you update PR so it builds with current code? Thanks!

[timrc-git]

Hi @QubitPi if you do something like:
PREFIX=/usr/local/ make
You'll get what you want.
The whole point of VAR ?= value vs VAR = value is that the former only sets the value if it's not already set. So that block of conditional sets that you changed was to allow overrides from the commandline. e.g. PREFIX=/usr/local PERL_PREFIX=/opt make would let you install most things to /usr/local, but put the perl stuff in /opt.

Note: I added the other changes to timrc-git/mdbm.