win32: build static library

Fixes linker failure on test/run_output.exe

src/output/plugins/meson.build

@@ -141,6 +141,7 @@ if is_windows
   wasapi_dep = [
     c_compiler.find_library('ksuser', required: true),
     c_compiler.find_library('ole32', required: true),
+    win32_dep,
   ]
 else
   wasapi_dep = dependency('', required: false)

src/win32/meson.build

@@ -0,0 +1,17 @@
+if not is_windows
+  win32_dep = declare_dependency('', required: false)
+  subdir_done()
+endif
+
+win32 = static_library(
+  'win32',
+  'ComWorker.cxx',
+  include_directories: inc,
+)
+
+win32_dep = declare_dependency(
+  link_with: win32,
+  dependencies: [
+    thread_dep,
+  ],
+)