Add stack.c to Visual Studio project.
<ClCompile Include="..\..\..\libyara\scan.c" />
<ClCompile Include="..\..\..\libyara\scanner.c" />
<ClCompile Include="..\..\..\libyara\sizedstr.c" />
+ <ClCompile Include="..\..\..\libyara\stack.c" />
<ClCompile Include="..\..\..\libyara\stopwatch.c" />
<ClCompile Include="..\..\..\libyara\stream.c" />
<ClCompile Include="..\..\..\libyara\strutils.c" />
