[TestBase.runCmd] Better error message when runCmd fails.

Summary:
Before:
    AssertionError: False is not True : Process is launched successfully

After:
    AssertionError: False is not True : Command 'run a.out' failed.
    >>> error: invalid target, create a target using the 'target create' command
    >>> Process could not be launched successfully

Reviewers: clayborg

Reviewed By: clayborg

Subscribers: lldb-commits, vharron

Differential Revision: http://reviews.llvm.org/D9948

llvm-svn: 238363
diff --git a/lldb/test/linux/builtin_trap/TestBuiltinTrap.py b/lldb/test/linux/builtin_trap/TestBuiltinTrap.py
index a81683c9..7bdeabb 100644
--- a/lldb/test/linux/builtin_trap/TestBuiltinTrap.py
+++ b/lldb/test/linux/builtin_trap/TestBuiltinTrap.py
@@ -43,7 +43,7 @@
                                                  num_expected_locations=1,
                                                  loc_exact=True)
 
-        self.runCmd("run", RUN_SUCCEEDED)
+        self.runCmd("run", RUN_FAILED)
 
         # The stop reason of the thread should be breakpoint.
         self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
@@ -54,7 +54,7 @@
         self.expect('bt', substrs = ['bar', 'main'])
 
         # go up one frame
-        self.runCmd("up", RUN_SUCCEEDED)
+        self.runCmd("up", RUN_FAILED)
 
         # evaluate a local
         self.expect('p foo', substrs = ['= 5'])