frysk-core dejagnu support

[Stan Cox <scox at redhat dot com>]

There is now basic dejagnu support in frysk-core roughly modeled after
the toolchain dejagnu support.  For example in frysk-core 'make check',
or more specifically 'make check-DEJAGNU', yields:
                === expr Summary ===
 # of expected passes            20

So this might be an option for any tests which are of the form:
 1. run something which generates output
 2. check if the output matches a pattern

1. frysk-core/testsuite/lib/frysk.exp is intended to be general purpose
tcl/expect procs which are used by the testsuites.  It is modeled after
gdb.exp, gcc.exp.
2. frysk-core/testsuite/expr/expr.exp has some expression tests.

Adding new tests:
0. New expression tests could be added to expr.exp.
1. A new test suite, e.g. breakpoint tests, could be added by creating a
new breaks.exp file modeled after expr.exp and adding necessary support
to frysk.exp.

resources: 
1. man expect (the .exp files are a combination of expect and tcl)
2. tcl docs (http://tmml.sourceforge.net/doc/tcl/)
3. dejagnu docs (runtest is the dejagnu driver, which is written in tcl)
(http://www.gnu.org/software/dejagnu/manual/)