Break up the dejagnu logic so that we can parallelize the testsuite.
This takes a page from gcc & gdb where each .exp is run in isolation
instead of in serial.
For most targets, this doesn't make much of a difference as they only
have a single .exp. A few (like cris & frv) have multiple .exp though
and will see a bit of a speed up.
The real gain is when testing a multitarget build. This way we can
run all the targets in parallel and cut the execution time a bit.
On my system, it goes from ~155sec to ~100sec.
We can gain further speedups by splitting up some of the larger .exp
files into smaller groups. We'll do that in a followup though.
Leverage the new per-port toolchain settings to initialize the env
for eeach set of tests. This allows us to run all the tests in a
multitarget build if the user sets up the vars. If they don't, we
can still skip all the tests.
Gas does not support multitarget builds -- it still only supports
a single input & output format. ld is a bit better, but requires
manual flags to select the right output. This makes it impossible
to run the complete testsuite in a multitarget build.
To address this limitation, create a suite of FOR_TARGET variables
so these can be set to precompiled as & ld programs. It requires
a bit of setup ahead of time, but it's a one-time cost, and makes
running the full testsuite at once much easier.
The tests assume that the cwd is the objdir directory and write its
intermediates to there all the time. When using runtest's --objdir
setting though, this puts the files in the wrong place. This isn't
a big problem currently as we never change --objdir, but in order to
support parallel test execution, we're going to start setting that
option, so clean up the code ahead of time.
We also have to tweak some of the cris tests which were making
assumptions about the argv[0] value.
Now that we have the common automake build with support for build-time
programs working, we can integrate the common tests into the default
`make check` flow.
