gbuild-to-ide: MSVC 2012 no longer supported, replace with 2015

Of course not tested in any way but with any luck the project file
format hasn't changed and it will "just work".

Change-Id: I81c5043259feeabd69ef31ea7ef160901ac7ebdc

Makefile.in

@@ -421,8 +421,8 @@ endef
 $(foreach ide,\
 	debug \
 	kdevelop \
-	vs2012 \
 	vs2013 \
+	vs2015 \
 	vim \
 	xcode \
 	qtcreator \

bin/gbuild-to-ide

@@ -833,7 +833,7 @@ class VisualStudioIntegrationGenerator(IdeIntegrationGenerator):
         }
 
     def retrieve_toolset(self, ide):
-        ide_toolset_map = {'vs2012': 'v110', 'vs2013': 'v120'}
+        ide_toolset_map = {'vs2013': 'v120', 'vs2015': 'v140'}
         return ide_toolset_map[ide]
 
     def module_make_command(self, targets):
@@ -1705,8 +1705,8 @@ if __name__ == '__main__':
         'eclipsecdt': EclipseCDTIntegrationGenerator,
         'kdevelop': KdevelopIntegrationGenerator,
         'xcode': XcodeIntegrationGenerator,
-        'vs2012': VisualStudioIntegrationGenerator,
         'vs2013': VisualStudioIntegrationGenerator,
+        'vs2015': VisualStudioIntegrationGenerator,
         'vim': VimIntegrationGenerator,
         'debug': DebugIntegrationGenerator,
         'qtcreator': QtCreatorIntegrationGenerator,