Revert to using a wrapper when starting Audacity

But, this time use a "C" wrapper as posited by Paul in:

   https://bugzilla.audacityteam.org/show_bug.cgi?id=543#c6

Doing so should bypass the execve()/decontruction issue and
still allow entitlements to work.

This also sets the build system to Legacy so that a "clean"
action will not produce:

   error: Could not delete '...' because it was not created by
          the build system.

And, I'm not sure why the deployment target was 10.9, but it
should have been 10.7.

mac/Audacity.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings

@@ -2,6 +2,8 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
 	<key>IDEWorkspaceSharedSettings_AutocreateContextsIfNeeded</key>
 	<false/>
 </dict>