webp 1.3 changed the filenames on windows to include a `lib` prefix
(ie libwebp.lib rather than webp.lib) now this is a common thing
on linux and cmake has a `CMAKE_FIND_LIBRARY_PREFIXES` variable that
has a list of prefixes to look for during a `find_library` call.
`CMAKE_FIND_LIBRARY_PREFIXES` gets set during the call to the
`project` method in the main CMakeLists of a project. Now for windows
`lib` is *not* a common prefix by CMake, and it doesn't add "lib" to
CMAKE_FIND_LIBRARY_PREFIXES during that call.
so find library doesn't look for it, the libs are not found and an
unhappy time is had by all. Now the most obvious solution would be to
pass `-DCMAKE_FIND_LIBRARY_PREFIXES=lib` to CMake to sidestep this
however, the `project` call will set the variable overwriting
anything you passed through the CLI.
So the fix here is to have `find_library` counter-intuitively look
for both `libwebp` and `webp`
3735a4d104