Parse preprocessor directives within structs

Previously, this would result in an error being raised.

Author: hughsk

lib/index.js

@@ -756,6 +756,11 @@ function parser() {
         , function() { state.scope.enter(); return Advance }
         , advance('{')
         , function() {
+            if(token.type === 'preprocessor') {
+              state.fake(adhoc())
+              tokens.shift()
+              return
+            }
             if(token.data === '}') {
               state.scope.exit()
               tokens.shift()