Fixed the LIBS macro definition.

src/sbbs3/Makefile.gnu

@@ -54,11 +54,11 @@ DELETE	=	rm -f -v
 OUTLIB	=	-o
 
 ifeq ($(os),freebsd)	# FreeBSD
-LIBS	=	-pthread
+LIBS	:=	-pthread
 CFLAGS	:=	-pthread
 else			        # Linux / Other UNIX
 CFLAGS	:=	-DJAVASCRIPT -I../mozilla/js/src
-LIBS	=	$(LIBDIR)/libpthread.a
+LIBS	:=	$(LIBDIR)/libpthread.a
 endif
 
 endif   # Unix (end)
@@ -67,12 +67,12 @@ ifdef DEBUG
 CFLAGS	:=	$(CFLAGS) -g -O0 -D_DEBUG 
 LIBODIR	:=	$(LIBODIR).debug
 EXEODIR	:=	$(EXEODIR).debug
-LIBS	=	$(LIBS) ../mozilla/js/src/Linux_All_DBG.OBJ/libjs.a
+LIBS	:=	$(LIBS) ../mozilla/js/src/Linux_All_DBG.OBJ/libjs.a
 else
 LFLAGS	:=	$(LFLAGS) -S
 LIBODIR	:=	$(LIBODIR).release
 EXEODIR	:=	$(EXEODIR).release
-LIBS	=	$(LIBS) ../mozilla/js/src/Linux_All_OPT.OBJ/libjs.a
+LIBS	:=	$(LIBS) ../mozilla/js/src/Linux_All_OPT.OBJ/libjs.a
 endif
 
 include targets.mak		# defines all targets