Report UNRESOLVED on failures while detecting Cell/B.E.

Report UNRESOLVED on failures while detecting Cell/B.E.

The gdb.cell testcases use the predicate skip_cell_tests defined in
lib/cell.exp to determine whether Cell/B.E. test cases ought to be
run. This tests verifies that we have a toolchain that supports
generating combined Cell/B.E. binaries, and that the target machine
actually is a Cell/B.E.

In order to do so, a small test program is built and run (under the
debugger).  Any failure is taken as a sign that we don't have a
Cell/B.E. machine and the tests are to be skipped.

This has the unfortunate effect that a serious bug in GDB that causes
internal compiler errors even on the trivial test program does not
lead to any failures in the testsuite, since now all gdb.cell test
are simply skipped.

This patch changes skip_cell_tests to at least report UNRESOLVED
in cases where execution of the test program fails in unexpected
ways.

testsuite/ChangeLog:

	* lib/cell.exp (skip_cell_tests): Report UNRESOLVED on unexpected
	failures to run the test program under GDB.