Merge pull request #426 from drodriguez/include-string-for-memcpy

Add string.h for memcpy in Data.swift.
diff --git a/dispatch/dispatch.h b/dispatch/dispatch.h
index 1901226..d148140 100644
--- a/dispatch/dispatch.h
+++ b/dispatch/dispatch.h
@@ -37,6 +37,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdarg.h>
+#include <string.h>
 #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 #include <unistd.h>
 #endif