Add a function to return the pointer type for a given triple.

Also use a slightly tidier naming convention for such functions.

lib/codegen/src/isa/call_conv.rs

@@ -21,7 +21,7 @@ pub enum CallConv {
 
 impl CallConv {
     /// Return the default calling convention for the given target triple.
-    pub fn default_for_triple(triple: &Triple) -> Self {
+    pub fn triple_default(triple: &Triple) -> Self {
         match triple.default_calling_convention() {
             // Default to System V for unknown targets because most everything
             // uses System V.

lib/codegen/src/isa/mod.rs

@@ -208,7 +208,7 @@ pub trait TargetIsa: fmt::Display + Sync {
 
     /// Get the default calling convention of this target.
     fn default_call_conv(&self) -> CallConv {
-        CallConv::default_for_triple(self.triple())
+        CallConv::triple_default(self.triple())
     }
 
     /// Get the pointer type of this ISA.