Fix typo "phtreads" to "pthreads"
Fix typo "phtreads" to "pthreads"

Closes issue #5349

Signed-off-by: Artur Allmann <138117079405a9db7be75f1eb6fa682462ff5aaf@tptlive.ee>

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