- move libc checks from busybox.h to platform.h

- add ATTRIBUTE_ALWAYS_INLINE, endian handling for DEC UNIX, some more
  compiler dependent defines to platform.h
- add conditional bb_setpgrp define to platform.h
- remove superfluous specifying args from "#define fdprintf dprintf"

include/busybox.h

@@ -15,16 +15,8 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
-#if __GNU_LIBRARY__ < 5 && \
-    !defined(__dietlibc__) && \
-    !defined(_NEWLIB_VERSION)
-#error "Sorry, this libc version is not supported :("
-#endif
-
 extern const char BB_BANNER[];
 
-#include <features.h>
-
 /* Pull in the utility routines from libbb */
 #include "libbb.h"