Fix build in 5.1 tree. to_string doesn't exist in bionic in 5.1.

Change-Id: If10b76f7a2b695c4be470812e048c66f5920d798
diff --git a/partition.cpp b/partition.cpp
index 7ae43ba..78c68db 100755
--- a/partition.cpp
+++ b/partition.cpp
@@ -422,7 +422,10 @@
 		else
 			return true;
 	} else if (Mount_Point == "auto") {
-		Mount_Point = "/auto" + to_string(auto_index);
+		Mount_Point = "/auto";
+		char autoi[5];
+		sprintf(autoi, "%i", auto_index);
+		Mount_Point += autoi;
 		Backup_Path = Mount_Point;
 		Storage_Path = Mount_Point;
 		Backup_Name = Mount_Point.substr(1);
diff --git a/twrp.cpp b/twrp.cpp
index cf519bb..37053d2 100755
--- a/twrp.cpp
+++ b/twrp.cpp
@@ -45,7 +45,7 @@
 #include "partitions.hpp"
 
 #ifdef USE_OLD_BASE_INCLUDE
-#include <base/strings.h>
+#include <strings.h>
 #else
 #include <android-base/strings.h>
 #endif