Windows: Use EXEPREP and DLLPREP macros for processing binaries

Once DLLs and EXEs are built, they need to have their manifests
processed and signed.  These steps are encapsulated in the EXEPREP and
DLLPREP Makefile macros.  Use them instead of invoking each processing
macro individually.

lib/com_err/NTMakefile

@@ -52,17 +52,13 @@ $(COMERRDLL): $(libcomerr_OBJs) $(OBJ)\libcom_err-version.res
 	$(DLLGUILINK_C) -out:$(COMERRDLL) -implib:$(LIBCOMERR) $** \
 		$(LIBROKEN) \
 		-def:libcom_err-exports.def
-	$(_VC_MANIFEST_EMBED_DLL)
-	$(_VC_MANIFEST_CLEAN)
-	$(_CODESIGN)
+	$(DLLPREP)
 
 !endif
 
 $(BINDIR)\compile_et.exe:  $(OBJ)\parse.obj $(OBJ)\lex.obj $(OBJ)\compile_et.obj
 	$(EXECONLINK) $(LIBROKEN) $(LIBVERS)
-	$(_VC_MANIFEST_EMBED_EXE)
-	$(_VC_MANIFEST_CLEAN)
-	$(_CODESIGN)
+	$(EXEPREP)
 
 $(OBJ)\parse.obj: $(OBJ)\parse.c
 	$(C2OBJ) -I$(SRC)\$(RELDIR)