Color EBB arguments.

When coloring registers for a branch instruction, also make sure that
the values passed as EBB arguments are in the registers expected by the
EBB.

The first time a branch to an EBB is processed, assign the EBB arguments
to the registers where the branch arguments already reside so no
regmoves are needed.

lib/cretonne/src/regalloc/diversion.rs

@@ -61,7 +61,7 @@ impl RegDiversions {
         self.current.iter().find(|d| d.value == value)
     }
 
-    /// Get all current diversion.
+    /// Get all current diversions.
     pub fn all(&self) -> &[Diversion] {
         self.current.as_slice()
     }