Demangle exception call stack for PADDLE_ENFORCE

[gangliao]

fix #3462

After this PR, if we meet some exceptions like this:

TEST(ENFORCE_USER_DEFINED_CLASS, EQ) {
  Dims a{{1, 3, 3, 4}}, b{{1, 2, 3, 4}};
  PADDLE_ENFORCE_EQ(a, b);
}

Call Stack:

: [ RUN      ] ENFORCE_USER_DEFINED_CLASS.EQ
68: unknown file: Failure
68: C++ exception with description "enforce a == b failed, [1, 3, 3, 4] != [1, 2, 3, 4]
68:  at [/Users/liaogang/baidu/Paddle/paddle/platform/enforce_test.cc:210]
68: PaddlePaddle Call Stacks:
68: 0          0x1051a58e0p paddle::platform::EnforceNotMet::EnforceNotMet(std::exception_ptr, char const*, int) + 768
68: 1          0x1051a4f79p ENFORCE_USER_DEFINED_CLASS_EQ_Test::TestBody() + 377
68: 2          0x1051b957bp void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) + 75
68: 3          0x1051b94cep testing::Test::Run() + 254
68: 4          0x1051ba4e2p testing::TestInfo::Run() + 306
68: 5          0x1051bad73p testing::TestCase::Run() + 275
68: 6          0x1051c2e59p testing::internal::UnitTestImpl::RunAllTests() + 1241
68: 7          0x1051c27c0p bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) + 80
68: 8          0x1051c271ep testing::UnitTest::Run() + 174
68: 9          0x1051d40d1p main + 49
68: 10      0x7fffa9e0c235p start + 1
68: 11                 0x1p " thrown in the test body.
68: [  FAILED  ] ENFORCE_USER_DEFINED_CLASS.EQ (0 ms)

[reyoung]

LGTM++