[ios, macos] Look even more widely for IB designables agent

The IBDesignablesAgent helper process has been renamed to IBAgent as of the Xcode 10 GM seed, so cast an even wider net when trying to detect it.

platform/darwin/src/NSProcessInfo+MGLAdditions.m

@@ -3,7 +3,8 @@
 @implementation NSProcessInfo (MGLAdditions)
 
 - (BOOL)mgl_isInterfaceBuilderDesignablesAgent {
-    return [self.processName hasPrefix:@"IBDesignablesAgent"];
+    NSString *processName = self.processName;
+    return [processName hasPrefix:@"IBAgent"] || [processName hasPrefix:@"IBDesignablesAgent"];
 }
 
 @end

platform/macos/CHANGELOG.md

@@ -7,7 +7,9 @@
 * Added an `MGLSymbolStyleLayer.symbolZOrder` property for forcing point features in a symbol layer to be layered in the same order that they are specified in the layer’s associated source. ([#12783](https://github.com/mapbox/mapbox-gl-native/pull/12783))
 
 ### Other changes	
+
 * Fixed an issue where `-[MGLMapSnapshotter startWithQueue:completionHandler:]` failed to call its completion handler in some cases. ([#12355](https://github.com/mapbox/mapbox-gl-native/pull/12355))
+* Fixed an issue where `MGLMapView` produced a designable error in Interface Builder storyboards in Xcode 10. ([#12883](https://github.com/mapbox/mapbox-gl-native/pull/12883))
 
 # 0.11.0 - September 13, 2018