Make GNUC-compatible compilers use the right mbedtls_t_udbl again on Aarch64 builds.
Make GNUC-compatible compilers use the right mbedtls_t_udbl again on Aarch64 builds.

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