Add error checking to aapt for split generation

Change-Id: Ica627db6a671f6a6c35f98bfd9c03598ffe103ce
diff --git a/tools/aapt/SourcePos.h b/tools/aapt/SourcePos.h
index 4ce817f..13cfb9d 100644
--- a/tools/aapt/SourcePos.h
+++ b/tools/aapt/SourcePos.h
@@ -21,6 +21,8 @@
     void warning(const char* fmt, ...) const;
     void printf(const char* fmt, ...) const;
 
+    bool operator<(const SourcePos& rhs) const;
+
     static bool hasErrors();
     static void printErrors(FILE* to);
 };