Make Profiler compile on Windows7.1SDK

Committed changes (afaik) will not affect original build environment.

To compile OpenCover.Profiler on Windows7.1SDK platform toolset using
VS2010 and/or SharpDevelop:

1) Instal Windows 7.1 SDK

2) In OpenCover.Profiler.vcxproj change all
-    <PlatformToolset>v110</PlatformToolset>
+    <PlatformToolset>Windows7.1SDK</PlatformToolset>

3) In OpenCover.Profiler project properties
define _TOOLSETV71 preprocessor symbol for
C++ Preprocessor AND
MIDL Preprocessor