env: re-add support for auto-completion

Currently, only basic completion is supported (no globs), but this is
what we had previously.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/common/command.c b/common/command.c
index ef4a081..b3ec510 100644
--- a/common/command.c
+++ b/common/command.c
@@ -162,7 +162,6 @@
 
 int var_complete(int argc, char * const argv[], char last_char, int maxv, char *cmdv[])
 {
-#if 0 /* need to reimplement */
 	static char tmp_buf[512];
 	int space;
 
@@ -173,7 +172,7 @@
 
 	if (!space && argc == 2)
 		return env_complete(argv[1], maxv, cmdv, sizeof(tmp_buf), tmp_buf);
-#endif
+
 	return 0;
 }