Force C# 2.0 support within NDesk.Options.dll.
Force C# 2.0 support within NDesk.Options.dll.

	* Makefile.am: Ensure that NDesk.Options.dll can be built under a C# 2.0
	  compiler by specifying -langversion:ISO-2.

MikeJansen/NDesk.Options.StrongNamed,chakrit/ndesk-options-mirror,MikeJansen/NDesk.Options.StrongNamed,MikeJansen/NDesk.Options.StrongNamed,chakrit/ndesk-options-mirror