* Fix git on ubuntu, first cut
Spack needs to pass information about where the linker
can find `libintl`. We're currently using `LDFLAGS` to do so.
The `LDFLAGS` info is pasted into the command line upstream
of the a file (`libgit.a`) that includes unresolved symbols that
need that library. This fails on Ubuntu, although it seems to
work on CentOS (see #6841).
This change allows git to build on a Ubuntu 16.04.3 droplet.
TODO: test on other platforms...
* Add a bit of useful commentary
ffa20d2171