[mtouch] Incremental builds (--fastdev) is the same as compiling all assemblies to dynamic libraries.

tools/mtouch/mtouch.cs

@@ -1143,7 +1143,7 @@ namespace Xamarin.Bundler
 			{ "enable-repl:", "Enable REPL support (simulator and not linking only)", v => { app.EnableRepl = ParseBool (v, "enable-repl"); }, true /* this is a hidden option until we've actually used it and made sure it works as expected */ },
 			{ "pie:", "Enable (default) or disable PIE (Position Independent Executable).", v => { app.EnablePie = ParseBool (v, "pie"); }},
 			{ "compiler=", "Specify the Objective-C compiler to use (valid values are gcc, g++, clang, clang++ or the full path to a GCC-compatible compiler).", v => { app.Compiler = v; }},
-			{ "fastdev", "Build an app that supports fastdev (this app will only work when launched using Xamarin Studio)", v => { app.FastDev = true; }},
+			{ "fastdev", "Build an app that supports fastdev (this app will only work when launched using Xamarin Studio)", v => { app.AddAssemblyBuildTarget ("@all=dynamiclibrary"); }},
 			{ "force-thread-check", "Keep UI thread checks inside (even release) builds", v => { app.ThreadCheck = true; }},
 			{ "disable-thread-check", "Remove UI thread checks inside (even debug) builds", v => { app.ThreadCheck = false; }},
 			{ "debug:", "Generate debug code in Mono for the specified assembly (set to 'all' to generate debug code for all assemblies, the default is to generate debug code for user assemblies only)",