Fix outcome file leak if execute_tests exits early
Fix outcome file leak if execute_tests exits early

If there was a fatal error (bizarre behavior from the standard
library, or missing test data file), execute_tests did not close the
outcome file. Fix this.

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