tests: Skip SPARC tests if the required binaries are missing

The full-system SPARC tests depend on several binaries that aren't
generally available to the wider community. Flag the tests as skipped
instead of failed if these binaries can't be found.

tests/configs/t1000-simple-atomic.py

@@ -31,7 +31,11 @@ from m5.objects import *
 m5.util.addToPath('../configs/common')
 import FSConfig
 
-system = FSConfig.makeSparcSystem('atomic')
+try:
+    system = FSConfig.makeSparcSystem('atomic')
+except IOError as e:
+    skip_test(reason=str(e))
+
 system.voltage_domain = VoltageDomain()
 system.clk_domain = SrcClockDomain(clock = '1GHz',
                                    voltage_domain = system.voltage_domain)