Make bsd make happy

Index: Makefile.pre.in
--- Makefile.pre.in.orig
+++ Makefile.pre.in
@@ -534,8 +534,6 @@ LIBMPDEC_OBJS= \
 		Modules/_decimal/libmpdec/numbertheory.o \
 		Modules/_decimal/libmpdec/sixstep.o \
 		Modules/_decimal/libmpdec/transpose.o
-		# _decimal does not use signaling API
-		# Modules/_decimal/libmpdec/mpsignal.o
 
 LIBMPDEC_HEADERS= \
 		$(srcdir)/Modules/_decimal/libmpdec/basearith.h \