Windows: Install runtime dependencies with Neovim binary

Look for runtime dependencies diff.exe and win32yank.exe (and
recursively for DLL dependencies) and install them with nvim.exe. If a
dependency is missing a warning will be issued.

src/nvim/CMakeLists.txt

@@ -292,18 +292,40 @@ target_link_libraries(nvim ${NVIM_EXEC_LINK_LIBRARIES})
 install_helper(TARGETS nvim)
 
 if(WIN32)
-  # Copy DLLs to bin/ and install them along with nvim
-  add_custom_target(nvim_dll_deps ALL DEPENDS nvim
+  # Copy DLLs and third-party tools to bin/ and install them along with nvim
+  add_custom_target(nvim_runtime_deps ALL
+    COMMAND ${CMAKE_COMMAND} -E copy_directory ${PROJECT_BINARY_DIR}/windows_runtime_deps/
+      ${CMAKE_RUNTIME_OUTPUT_DIRECTORY})
+  install(DIRECTORY ${PROJECT_BINARY_DIR}/windows_runtime_deps/
+    DESTINATION ${CMAKE_INSTALL_BINDIR})
+
+  foreach(BIN win32yank.exe)
+    unset(BIN_PATH CACHE)
+    find_program(BIN_PATH ${BIN})
+    if(NOT BIN_PATH)
+      message(FATAL_ERROR "Unable to find external dependency ${BIN}")
+    endif()
+
+    add_custom_target(external_${BIN}
+      COMMAND ${CMAKE_COMMAND} -E make_directory ${PROJECT_BINARY_DIR}/windows_runtime_deps
+      COMMAND ${CMAKE_COMMAND}
+        "-DCMAKE_PREFIX_PATH=${CMAKE_PREFIX_PATH}"
+        -DBINARY="${BIN_PATH}"
+        -DDST=${PROJECT_BINARY_DIR}/windows_runtime_deps
+        -P ${PROJECT_SOURCE_DIR}/cmake/WindowsDllCopy.cmake
+      COMMAND ${CMAKE_COMMAND} -E copy ${BIN_PATH} ${PROJECT_BINARY_DIR}/windows_runtime_deps/
+      COMMENT "${BIN_PATH}")
+    add_dependencies(nvim_runtime_deps "external_${BIN}")
+  endforeach()
+
+  add_custom_target(nvim_dll_deps DEPENDS nvim
     COMMAND ${CMAKE_COMMAND} -E make_directory ${PROJECT_BINARY_DIR}/windows_runtime_deps
     COMMAND ${CMAKE_COMMAND}
       "-DCMAKE_PREFIX_PATH=${CMAKE_PREFIX_PATH}"
       -DBINARY="${PROJECT_BINARY_DIR}/bin/nvim${CMAKE_EXECUTABLE_SUFFIX}"
       -DDST=${PROJECT_BINARY_DIR}/windows_runtime_deps
-      -P ${PROJECT_SOURCE_DIR}/cmake/WindowsDllCopy.cmake
-    COMMAND ${CMAKE_COMMAND} -E copy_directory ${PROJECT_BINARY_DIR}/windows_runtime_deps/
-      ${CMAKE_RUNTIME_OUTPUT_DIRECTORY})
-  install(DIRECTORY ${PROJECT_BINARY_DIR}/windows_runtime_deps/
-    DESTINATION ${CMAKE_INSTALL_BINDIR})
+      -P ${PROJECT_SOURCE_DIR}/cmake/WindowsDllCopy.cmake)
+  add_dependencies(nvim_runtime_deps nvim_dll_deps)
 endif()
 
 if(CLANG_ASAN_UBSAN)