* pe-dll.c: New file; direct support for PE DLLs

	* pe-dll.c: New file; direct support for PE DLLs
	* deffile.h: New file; direct support for PE DLLs
	* deffilep.y: New file; direct support for PE DLLs
	* emultempl/pe.em: add direct support for PE DLLs
	* configure.tgt: allow target-specific extra files
	* configure.in: allow target-specific extra files
	* ldlang.c (lang_add_assignment): return the assignment so that
 	one can change the value later based on the object files (pe-dll
 	DEF files do this)
	* ldint.texinfo: add section for emulation walkthrough