Add missing includes.

Test: Builds.
Change-Id: Ia8b79154902503cdd774dc3b4523466123b4324c
diff --git a/libunwindstack/Symbols.cpp b/libunwindstack/Symbols.cpp
index 14ebdbb..e3c15a2 100644
--- a/libunwindstack/Symbols.cpp
+++ b/libunwindstack/Symbols.cpp
@@ -17,6 +17,7 @@
 #include <elf.h>
 #include <stdint.h>
 
+#include <algorithm>
 #include <string>
 
 #include <unwindstack/Memory.h>