Improve the building of eclib (shared/static objects) #3358
Description
After sitting waiting for some answers on the last thread about this on debian-sage
I decided to go ahead. This patch do not add versionning for debian as it seems
to cause problem on other OS. It builds static objects (libraries and executables)
without any pic flag and shared object with pic flag on linux. I respected the earlier
setting where the flag is set in spkg-install and it is set to nothing on OS X and
CYGWIN although I think it should be set as well on this platform.
I also move executables in a created bin directory for convenience (this directory
is created by the Makefile).
I cleaned the spkg-install to accommodate the changes and added a few fix that I
thought necessary. -fPIC to -fpic, those are 2 slightly different flags, I don't
think I should go on the technical differences between them. I also cleaned
a conditional block were linux specific code would be executed on darwin - probably
without harm but still.
CC: @timabbott
Component: build
Reviewer: François Bissey
Issue created by migration from https://trac.sagemath.org/ticket/3358