Add missing includes.

Test: Builds.
Change-Id: Ia8b79154902503cdd774dc3b4523466123b4324c
diff --git a/libunwindstack/RegsMips.cpp b/libunwindstack/RegsMips.cpp
index 2e6908c..14a4e31 100644
--- a/libunwindstack/RegsMips.cpp
+++ b/libunwindstack/RegsMips.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <stdint.h>
+#include <string.h>
 
 #include <functional>