[TestGdbRemoteRegisterState] Do not flip ARM *psr register in the test

[sivachandra]

Summary

Not all of that register is readable/writable in user mode. This means
that even if the inferior is stopped, parts of the register could be
changing. So, do not flip this register to check if its value can be
restored.

[tberghammer]

Looks good (why we haven't hit this issue before?)

[chaoren]

Only fails on older devices, I think.

[sivachandra]

Yes, it fails only on older Android API levels (which run older kernels). There also, it is flaky, not really 100% reproducible.

test/tools/lldb-server/gdbremote_testcase.py

def is_bit_flippable_register(self, reg_info):
             return False
         if ("container-regs" in reg_info) and (len(reg_info["container-regs"]) > 0):
             # Don't try to bit flip registers contained in another register.
             return False
         if re.match("^.s$", reg_info["name"]):
             # This is a 2-letter register name that ends in "s", like a segment register.
             # Don't try to bit flip these.
             return False
+        if re.match("^(c|)psr$", reg_info["name"]):
+            # This is an ARM program status register; don't flip it.
+            return False
         # Okay, this looks fine-enough.
         return True
 
     def read_register_values(self, reg_infos, endian, thread_id=None):
         self.assertIsNotNone(reg_infos)
         values = {}
 
         for reg_info in reg_infos: