Broken building on windows with CMake Ninja generator.

[mizvekov]

Building on windows with Ninja generator is currently broken, caused by recent change: #2085

The changes in OUTPUT_NAME causes the rules for both shared and static libraries to try to generate a file with the same name, uv.lib, resulting in cmake generating an ill-formed build.ninja.

Ninja produces the following diagnostics:

ninja: error: build.ninja:1006: multiple rules generate uv.lib [-w dupbuild=err]

For reference, see the output of this failing job: https://github.com/libuv/libuv/actions/runs/6203070753/job/16843050538

[vtjnash]

Fixed by #4185