aria: define SLA() as sl(a())
aria: define SLA() as sl(a())

This decreases the size with -Os by nearly 1k while
not hurting performance too much with -O2 and -O3

Before:
O	aria.o	ins
s	8784	41,408
2	11112	37,001
3	13096	27,438

After:
O	aria.o	ins
s	7976	43,865
2	10520	37,631
3	13040	28,146

(See previous commit for measurement details.)

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