[Gm2] change to linking mechanism

[Gaius Mulley]

Hi,

I've checked in a few changes which alter the linking mechanism to use
a series of archives rather than search for object files.  You can
still populate the appropriate install directories with objects (if
required).  Object files of the same name as modules will take
precedence but if they are not found then gm2 will use the library
archives (in the same way as gcc).

I've run the regression tests on Ubuntu 9.10 LP64 and all pass.
Although I have unearthed an optimisation bug -O2 (and higher) in
StrLen - which I'm hunting at present.  I've currently built all
libraries without any optimisation while this bug is being sought.

regards,
Gaius