New macro ASSERT_ALLOC to allocate memory in tests
New macro ASSERT_ALLOC to allocate memory in tests

The new macro ASSERT_ALLOC allocates memory with mbedtls_calloc and
fails the test if the allocation fails. It outputs a null pointer if
the requested size is 0. It is meant to replace existing calls to
mbedtls_calloc.

Mbed-TLS/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,NXPmicro/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls