fix build

use config.def.h mechanism
add SHELL in config.h

Makefile

@@ -8,12 +8,15 @@ OBJ = ${SRC:.c=.o}
 
 all: options st
 
-options:
+options: options
 	@echo st build options:
 	@echo "CFLAGS   = ${CFLAGS}"
 	@echo "LDFLAGS  = ${LDFLAGS}"
 	@echo "CC       = ${CC}"
 
+config.h:
+	cp config.def.h config.h
+
 .c.o:
 	@echo CC $<
 	@${CC} -c ${CFLAGS} $<