Upgrade to Rust 1.17.

- Remove some uses of 'static in const and static globals that are no
  longer needed.
- Use the new struct initialization shorthand.

lib/cretonne/src/regalloc/coloring.rs

@@ -99,8 +99,8 @@ impl Coloring {
         let mut ctx = Context {
             reginfo: isa.register_info(),
             encinfo: isa.encoding_info(),
-            domtree: domtree,
-            liveness: liveness,
+            domtree,
+            liveness,
             usable_regs: isa.allocatable_registers(func),
         };
         ctx.run(self, func, tracker)

lib/cretonne/src/regalloc/live_value_tracker.rs

@@ -70,9 +70,9 @@ impl LiveValueVec {
     fn push(&mut self, value: Value, endpoint: Inst, affinity: Affinity) {
         self.values
             .push(LiveValue {
-                      value: value,
-                      endpoint: endpoint,
-                      affinity: affinity,
+                      value,
+                      endpoint,
+                      affinity,
                   });
     }
 

lib/cretonne/src/regalloc/liverange.rs

@@ -208,8 +208,8 @@ impl LiveRange {
     /// The live range will be created as dead, but it can be extended with `extend_in_ebb()`.
     pub fn new(value: Value, def: ProgramPoint, affinity: Affinity) -> LiveRange {
         LiveRange {
-            value: value,
-            affinity: affinity,
+            value,
+            affinity,
             def_begin: def,
             def_end: def,
             liveins: Vec::new(),