It seems that with the new dll separation changes, winebuild is broken. I've been trying to build an app with winebuild, and it tries to open kernel32.dll.so instead of libkernel32.dll.so when trying to resolve the "import kernel32.dll" line of the spec file. This works for compiling wine, but not for compiling external apps that use the installed lib directory.
I'm not sure if I should fix winebuild to look for lib(name).dll.so or if I should change the dll makefiles to create the correct symlinks so that wine can compile or if we should make winebuild check for both lib(name).dll.so and (name).dll.so. For now, I'm doing the last case, which works fine, so I can submit that patch if you want it.
There is also the problem of dlls in the wine directory which are not found either, which I'm still working on.