Allow fw env tools to be available as library

Sometimes it can be useful to link the fw_ tools instead
of having the fw_setenv/fw_printenv installed.
Patch exports the tool as library and allowes to link it
with own programs.

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Tom Rini <trini@konsulko.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

tools/env/Makefile

@@ -23,10 +23,12 @@ endif
 always := fw_printenv
 hostprogs-y := fw_printenv
 
-fw_printenv-objs := fw_env.o fw_env_main.o \
+lib-y += fw_env.o \
 	crc32.o ctype.o linux_string.o \
 	env_attr.o env_flags.o aes.o
 
+fw_printenv-objs := fw_env_main.o $(lib-y)
+
 quiet_cmd_crosstools_strip = STRIP   $^
       cmd_crosstools_strip = $(STRIP) $^; touch $@