Fixed issue #44.

Removed unnesessary include <sys/types.h> from stdio.h, stdlib.h,
string.h, strings.h and time.h.

include/stddef.h

@@ -1,8 +1,22 @@
+#ifndef _STDDEF_H_
+#define _STDDEF_H_
+
+typedef int ptrdiff_t;
+
+#ifndef _SIZE_T
+#define _SIZE_T
+typedef unsigned size_t;
+#endif
+
+#ifndef NULL
+#define NULL    0
+#endif
 
 /* Offset of member MEMBER in a struct of type TYPE. */
-
 #if defined(__GNUC__) && __GNUC__ > 3
 #define offsetof(TYPE, MEMBER) __builtin_offsetof (TYPE, MEMBER)
 #else
 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE*)0)->MEMBER)
 #endif
+
+#endif /* _STDDEF_H_ */