libuv: macos: use posix poll instead of kqueue

Since commit 5420639a8d (cmExecuteProcessCommand: Replace cmsysProcess
with cmUVProcessChain, 2023-06-01, v3.28.0-rc1~138^2~8) we've observed
spurious process hangs in `uv__io_poll` waiting for `kqueue` to deliver
events on macOS.

Issue: #25839

Utilities/cmlibuv/CMakeLists.txt

@@ -191,8 +191,8 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     src/unix/bsd-ifaddrs.c
     src/unix/darwin.c
     src/unix/darwin-proctitle.c
-    src/unix/fsevents.c
-    src/unix/kqueue.c
+    src/unix/no-fsevents.c
+    src/unix/posix-poll.c
     src/unix/proctitle.c
     )
 endif()

Utilities/cmlibuv/include/uv/darwin.h

@@ -30,6 +30,9 @@
 # define UV_PLATFORM_SEM_T semaphore_t
 #endif
 
+#if 1 /* FIXME(#25839): use posix poll to avoid kqueue hangs on macOS.  */
+# include "posix.h"
+#else
 #define UV_HAVE_KQUEUE 1
 
 #define UV_IO_PRIVATE_PLATFORM_FIELDS                                         \
@@ -55,6 +58,8 @@
   int cf_error;                                                               \
   uv_mutex_t cf_mutex;                                                        \
 
+#endif
+
 #define UV_STREAM_PRIVATE_PLATFORM_FIELDS                                     \
   void* select;                                                               \
 

Utilities/cmlibuv/src/unix/darwin.c

@@ -41,6 +41,7 @@ static mach_timebase_info_data_t timebase;
 
 typedef unsigned char UInt8;
 
+#ifdef UV_HAVE_KQUEUE
 int uv__platform_loop_init(uv_loop_t* loop) {
   loop->cf_state = NULL;
 
@@ -54,6 +55,7 @@ int uv__platform_loop_init(uv_loop_t* loop) {
 void uv__platform_loop_delete(uv_loop_t* loop) {
   uv__fsevents_loop_delete(loop);
 }
+#endif
 
 
 static void uv__hrtime_init_once(void) {