Update TestChangeProcessGroup to remove obsolete workaround.

[chaoren]

Remove old line.

[chaoren]

I thought this was supposed to be fixed, but TestChangeProcessGroup, TestExpressionInSyscall, and TestRegisters just started failing for me recently because of this.

[labath]

We have been looking into these failures also, and the cause is the recent changes, which make it impossible to evaluate c(++) expression in assembly language frames (see D12962). This is not the purpose of this test, but I don't think we should work around it as I believe a simple expression as "var = 1" should work regardless of the selected frame. I'd like to wait on the comments on the aforementioned patch before we put this in.

[labath]

(I wouldn't be opposed to temporarily XFAILing the failing tests, so they don't bother anyone running the test suite)

[tberghammer]

I committed in the fix mentioned by Pavel as rL248146

[chaoren]

Do we still need the original stepInstruction?

[chaoren]

Remove existing workaround.

[labath]

That shouln't be needed anymore, thanks.

test/functionalities/process_group/TestChangeProcessGroup.py

def setpgid(self):
         error = lldb.SBError()
         process = target.AttachToProcessWithID(listener, int(pid), error)
         self.assertTrue(error.Success() and process, PROCESS_IS_VALID)
 
         # set a breakpoint just before the setpgid() call
         lldbutil.run_break_set_by_file_and_line(self, 'main.c', self.line, num_expected_locations=-1)
 
         thread = process.GetSelectedThread()
-        # this gives a chance for the thread to exit the sleep syscall and sidesteps
-        # <https://llvm.org/bugs/show_bug.cgi?id=23659> on linux
-        thread.StepInstruction(False)
 
         # release the child from its loop
         self.expect("expr release_child_flag = 1", substrs = ["= 1"])
         process.Continue()
 
         # make sure the child's process group id is different from its pid
         self.expect("print (int)getpgid(0)", substrs = [pid], matching=False)