versioner: handle _FILE_OFFSET_BITS=64.

Compile headers with both -D_FILE_OFFSET_BITS=32 and -D_FILE_OFFSET_BITS=64.

Bug: http://b/30170081
Change-Id: I92651e075cc69bdc1a2581f99892c9a7fdcdb35b
Test: python run_tests.py
diff --git a/tools/versioner/src/DeclarationDatabase.cpp b/tools/versioner/src/DeclarationDatabase.cpp
index 8e8d84f..88f7b55 100644
--- a/tools/versioner/src/DeclarationDatabase.cpp
+++ b/tools/versioner/src/DeclarationDatabase.cpp
@@ -288,7 +288,7 @@
 
 std::string to_string(const CompilationType& type) {
   std::stringstream ss;
-  ss << to_string(type.arch) << "-" << type.api_level;
+  ss << to_string(type.arch) << "-" << type.api_level << " [fob = " << type.file_offset_bits << "]";
   return ss.str();
 }