VisualC: Add support for msvc toolset version

mesonbuild/compilers/c.py

@@ -1056,3 +1056,29 @@ class VisualStudioCCompiler(CCompiler):
             # and the can not be called.
             return None
         return vs32_instruction_set_args.get(instruction_set, None)
+
+    def get_toolset_version(self):
+        # See boost/config/compiler/visualc.cpp for up to date mapping
+        try:
+            version = int(''.join(self.version.split('.')[0:2]))
+        except:
+            return None
+        if version < 1310:
+            return '7.0'
+        elif version < 1400:
+            return '7.1' # (Visual Studio 2003)
+        elif version < 1500:
+            return '8.0' # (Visual Studio 2005)
+        elif version < 1600:
+            return '9.0' # (Visual Studio 2008)
+        elif version < 1700:
+            return '10.0' # (Visual Studio 2010)
+        elif version < 1800:
+            return '11.0' # (Visual Studio 2012)
+        elif version < 1900:
+            return '12.0' # (Visual Studio 2013)
+        elif version < 1910:
+            return '14.0' # (Visual Studio 2015)
+        elif version < 1920:
+            return '14.1' # (Visual Studio 2017)
+        return None