I am currently trying to build 3.6.7 and 3.7.1 using Intel 2019 and it is failing because Intel's implementation of C11, in particular stdatomic, is incomplete.  I receive many errors similar to the following, when it cannot find 'atomic_uintptr_t', which is not including in Intel's implementation:

```
In file included from ./Include/Python.h(56),
                 from ./Modules/_io/bufferedio.c(11):
./Include/pyatomic.h(33): error: identifier "atomic_uintptr_t" is undefined
      atomic_uintptr_t _value;
```

The current check in configure.ac is insufficient, as it only checks to see that the header and library exist and that it contains 'atomic_int'.  The configure.ac should be changed to either check for all the atomic types it uses (or at least atomic_uintprt_t) or, when `--with-icc` is enabled, it should set 'HAVE_STD_ATOMIC' to 0/false.