Fix rs codegen breakage from a field 'bool clear'

Before this fix, the overload resolution rules would accidentally attempt to call the accessor named clear() instead of the fn that would actually clear the message (Rust automatically prefers an inherent impl fn over a trait impl fn if both exist with the same name).

PiperOrigin-RevId: 713309633

rust/test/bad_names.proto

@@ -24,6 +24,7 @@ message Self {
   optional bool true = 3;
   optional string false = 4;
   repeated int32 match = 5;
+  optional bool clear = 6;
 }
 
 message Pub {

src/google/protobuf/compiler/rust/message.cc

@@ -775,7 +775,8 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
 
         impl $pb$::Clear for $Msg$ {
           fn clear(&mut self) {
-            self.as_mut().clear()
+            let mut m = self.as_mut();
+            $pb$::Clear::clear(&mut m)
           }
         }