Fix a path in the MSVC autobuild bat script
Explicitly mention WelsVP.lib as an additional dependency

This fixes building welsenc.dll from AutoBuild_Windows_VS2008.bat,
since the project interdependencies aren't taken into account
automatically in the linker commands when building one project at a
time.
Merge pull request #1085 from mstorsjo/fix-msvc-autobuild-script

Fix running the MSVC autobuild bat script