config_stack_protector_strong is needed for AWS Trusty 4.4

Failure reported in the ubuntu_qrt_kernel_security:

  FAIL: test_185_config_stack_protector_strong (__main__.KernelSecurityConfigTest)
  CONFIG_CC_STACKPROTECTOR_STRONG set
  ----------------------------------------------------------------------
  Traceback (most recent call last):
  File "./test-kernel-security.py", line 2350, in test_185_config_stack_protector_strong
  self.assertKernelConfig(config_option, expected)
  File "./test-kernel-security.py", line 207, in assertKernelConfig
  self.assertKernelConfigSet(name)
  File "./test-kernel-security.py", line 194, in assertKernelConfigSet
  '%s option was expected to be set in the kernel config' % name)
  AssertionError: CC_STACKPROTECTOR_STRONG option was expected to be set in the kernel config