Fix header file usage -- there were many unnecessary header files included in

busybox.h which slowed compiles.  I left only what was needed and then fixed up
all the apps to include their own header files.  I also fixed naming for pwd.h
and grp.h functions.  Tested to compile and run with libc5, glibc, and uClibc.
 -Erik

util-linux/fbset.c

@@ -31,6 +31,7 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <ctype.h>
+#include <string.h>
 #include <sys/ioctl.h>
 
 #define DEFAULTFBDEV  "/dev/fb0"