AAPT2: Bump version number to v2.18

Test: none
Change-Id: I6e3b4c95a7d7ba416ba368e5b19782dbffa04fd8
diff --git a/tools/aapt2/Main.cpp b/tools/aapt2/Main.cpp
index 5978cdd..c5d38ab 100644
--- a/tools/aapt2/Main.cpp
+++ b/tools/aapt2/Main.cpp
@@ -27,7 +27,7 @@
 static const char* sMajorVersion = "2";
 
 // Update minor version whenever a feature or flag is added.
-static const char* sMinorVersion = "17";
+static const char* sMinorVersion = "18";
 
 int PrintVersion() {
   std::cerr << "Android Asset Packaging Tool (aapt) " << sMajorVersion << "."