Support building with Visual Studio 2015

Adjust the way we detect the locale. As a result the minumum Windows
version supported by VS2015 and later is Windows Vista. Add some tweaks
to remove new compiler warnings. Remove documentation references to the
now obsolete msysGit.

Michael Paquier, somewhat edited by me, reviewed by Christian Ullrich.

Backpatch to 9.5

src/tools/msvc/MSBuildProject.pm

@@ -465,4 +465,27 @@ sub new
 	return $self;
 }
 
+package VC2015Project;
+
+#
+# Package that encapsulates a Visual C++ 2015 project file
+#
+
+use strict;
+use warnings;
+use base qw(VC2012Project);
+
+sub new
+{
+	my $classname = shift;
+	my $self      = $classname->SUPER::_new(@_);
+	bless($self, $classname);
+
+	$self->{vcver}           = '14.00';
+	$self->{PlatformToolset} = 'v140';
+	$self->{ToolsVersion}    = '14.0';
+
+	return $self;
+}
+
 1;