Fix build with newer nasm.

Index: Makefile.in
--- Makefile.in.orig
+++ Makefile.in
@@ -1487,7 +1487,7 @@ uninstall-man: uninstall-man1 uninstall-man5
 
 
 .asm.$(OBJEXT):
-	@NASM@ -f @NASM_FORMAT@ -o $@ -- $<
+	@NASM@ -f @NASM_FORMAT@ -o $@ $<
 
 # Tell versions [3.59,3.63) of GNU make to not export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.
