toolchain testing

  If you use my my fork of ABE from here:
https://gitlab.com/rsavoye/abe, here's how I'm running tests with a
branch of DejaGnu:

./abe.sh gcc=gcc.git~master --set
languages=c,c++,lto,go,fortran --build all --set runtestflags='--xml'
--excludecheck glibc --check all --disable update |& tee x

  Explanation of the options is:

--set languages=c,c++,lto,go,fortran
	specified which front ends to build. This is the default list, but here
as an example. I often just test with C for a quick test during
development to save time.

-set runtestflags='--xml'
	This add the --xml option to runtest, in this case output XML files
instead of the default sum files. This format is for. importing into a
database.

--excludecheck glib
	Something is slightly broken in ABE for native testing, it thinks it
needs to test glibc, which is wrong, The system glibc is used instead,
so don't try to test it. I'll get around to fixing it...

--disable update
	Once you have everything downloaded, it's good to not update the
sources when comparing test runs. This says don't update the source trees.

  Other stuff you can do to test DejaGnu branches is add the
"dejagnu=dejagnu.git@BRANCH" on the command line. This has
"gcc=gcc.git~master", which is obvious, but you can also do
"gcc=gcc.git~release-9.3.0", etc...

  The syntax is a bit convoluted, as it supports a lot of flexibility in
what you are building and testing. I wrote ABE when I got tired of
telling people how to build cross toolchains, so it was easier to write
a tool to do it instead. Plus ABE also plugs in nicely to CI systems, as
it was designed for that workflow.

	- rob -