Tune gcc stack growth parameter.

Use 4 instead of 8 -- latest gcc isn't doing tail-recursion
    optimizations on disk functions due to stack growth.
diff --git a/Makefile b/Makefile
index 3a24433..220eafa 100644
--- a/Makefile
+++ b/Makefile
@@ -30,7 +30,7 @@
 
 override CFLAGS = $(COMMONCFLAGS) -g -DMODE16=0
 CFLAGS16INC = $(COMMONCFLAGS) -DMODE16=1 -fno-jump-tables -fno-defer-pop \
-              $(call cc-option,$(CC),--param large-stack-frame=8,)
+              $(call cc-option,$(CC),--param large-stack-frame=4,)
 CFLAGS16 = $(CFLAGS16INC) -g
 
 TABLETMP=$(addprefix $(OUT), $(patsubst %.c,%.16.s,$(TABLESRC)))