modprobe: cleanup, incorporate Ashwini's fix for alias loading

Move <fnmatch.h> to toys.h, since it's POSIX.
Avoid duplicating code in an if/else block.
Terser error messages, spelling.
Don't always print the state.
diff --git a/toys.h b/toys.h
index 2f16596..31193a4 100644
--- a/toys.h
+++ b/toys.h
@@ -13,6 +13,7 @@
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <fnmatch.h>
 #include <grp.h>
 #include <inttypes.h>
 #include <limits.h>