tools: env: bug: config structs must be defined in tools library

fw_senten/fw_printenv can be compiled as a tools library,
excluding the fw_env_main object.

Reported-by: Stefano Babic <sbabic@denx.de>
Signed-off-by: Andreas Fenkart <andreas.fenkart@digitalstrom.com>

tools/env/fw_env.c

@@ -35,6 +35,10 @@
 
 #include "fw_env.h"
 
+struct common_args common_args;
+struct printenv_args printenv_args;
+struct setenv_args setenv_args;
+
 #define DIV_ROUND_UP(n, d)	(((n) + (d) - 1) / (d))
 
 #define min(x, y) ({				\

tools/env/fw_env_main.c

@@ -49,10 +49,6 @@ static struct option long_options[] = {
 	{NULL, 0, NULL, 0}
 };
 
-struct common_args common_args;
-struct printenv_args printenv_args;
-struct setenv_args setenv_args;
-
 void usage_printenv(void)
 {