Fixed issue #44.

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

include/strings.h

@@ -30,7 +30,10 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-#include <sys/types.h>
+#ifndef _SIZE_T
+#define _SIZE_T
+typedef unsigned size_t;
+#endif
 
 int      bcmp(const void *, const void *, size_t);
 void     bcopy(const void *, void *, size_t);