Make readLenType generally available. Fix some warnings around read(2).

include/global.h

@@ -73,6 +73,13 @@ typedef xchar boolean; /* 0 or 1 */
 #endif
 #endif
 
+/* Type for third parameter of read(2) */
+#if defined(BSD) || defined(ULTRIX)
+typedef int readLenType;
+#else /* e.g. SYSV, __TURBOC__ */
+typedef unsigned readLenType;
+#endif
+
 #ifndef TRUE /* defined in some systems' native include files */
 #define TRUE ((boolean) 1)
 #define FALSE ((boolean) 0)