ec/suite_b: Rename elem_less_than to elem_less_than_vartime.

Make it clearer that it is a variable-time operation.

src/ec/suite_b/ecdsa/verification.rs

@@ -158,7 +158,7 @@ impl EcdsaVerificationAlgorithm {
         if sig_r_equals_x(self.ops, &r, &x, &z2) {
             return Ok(());
         }
-        if self.ops.elem_less_than(&r, &self.ops.q_minus_n) {
+        if self.ops.elem_less_than_vartime(&r, &self.ops.q_minus_n) {
             let n = Elem::from(self.ops.n());
             self.ops.scalar_ops.common.elem_add(&mut r, &n);
             if sig_r_equals_x(self.ops, &r, &x, &z2) {

src/ec/suite_b/ops.rs

@@ -328,7 +328,7 @@ impl PublicScalarOps {
         a.limbs[..num_limbs] == b.limbs[..num_limbs]
     }
 
-    pub fn elem_less_than(&self, a: &Elem<Unencoded>, b: &PublicElem<Unencoded>) -> bool {
+    pub fn elem_less_than_vartime(&self, a: &Elem<Unencoded>, b: &PublicElem<Unencoded>) -> bool {
         let num_limbs = self.public_key_ops.common.num_limbs.into();
         limbs_less_than_limbs_vartime(&a.limbs[..num_limbs], &b.limbs[..num_limbs])
     }