Don't include mbedtls/platform.h unconditionally
Don't include mbedtls/platform.h unconditionally

Programs must not include mbedtls/platform.h if MBEDTLS_PLATFORM_C is
not defined. Test suites don't need to include mbedtls/platform.h
because helpers.function takes care of it.

This commit also removes a stray `;` which is technically not standard C.

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