Get VS 2015 to use const int definitions

VC++ up to VS 2015 RTM does not require explicit storage allocation for
static const integers declared in classes. VS 2015 Update 1 requires
these storage definitions in some cases. It's unclear exactly what
cases - simple tests work with and without the explicit storage
allocation.

Many previous versions of VC++ have theoretically *allowed* a
definition to supply storage, but tests on VC++ 2013 show that this
doesn't actually work correctly - it leads to duplicate definition
errors in Chromium. So, the change is scoped to VS 2015 only.

This change also updates the generated files to match the new generator.

TL;DR - this change is necessary in order for Chromium to build with
VS 2015 Update 1.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/google/protobuf/wire_format_lite.cc b/src/google/protobuf/wire_format_lite.cc
index 847e3500..7f1093c8 100644
--- a/src/google/protobuf/wire_format_lite.cc
+++ b/src/google/protobuf/wire_format_lite.cc
@@ -49,8 +49,10 @@ namespace google {
 namespace protobuf {
 namespace internal {
 
-#ifndef _MSC_VER    // MSVC doesn't like definitions of inline constants, GCC
-                    // requires them.
+
+#if !defined(_MSC_VER) || _MSC_VER >= 1900
+// Old version of MSVC doesn't like definitions of inline constants, GCC
+// requires them.
 const int WireFormatLite::kMessageSetItemStartTag;
 const int WireFormatLite::kMessageSetItemEndTag;
 const int WireFormatLite::kMessageSetTypeIdTag;