security/nss: unbreak on powerpc64 after r501212

crypto_primitives.c: In function 'swap8b':
crypto_primitives.c:31: error: 'SHA_MASK8' undeclared (first use in this
function)
crypto_primitives.c:31: error: (Each undeclared identifier is reported only
once
crypto_primitives.c:31: error: for each function it appears in.)
crypto_primitives.c:32: error: 'SHA_MASK16' undeclared (first use in this
function)

PR: 237841
Reported by: jhibbits