Update vcxproj files, fix debug builds (MSVC) (#841)

Update vcxproj files, fix debug builds (MSVC) (#841)

- Solution configuration Debug|Win32: Changed MultiThreadedDebug to
  MultiThreadedDebugDLL in rrdtool.vcxproj and rrdupdate.vcxproj.
  Now the RuntimeLibrary setting is the same as in librrd-4.vcxproj.
- Solution configuration Static Debug|Win32: Added double quotes around
  $(TargetDir), because there is a space in "Static Debug". Fixes
  failing copy commands of dlls by using "$(TargetDir)" now.