extract fixes from limited api tests

tools/install_libzmq.sh

@@ -6,8 +6,9 @@ LIBZMQ_VERSION=$(python buildutils/bundle.py)
 PYZMQ_DIR="$PWD"
 LICENSE_DIR="$PYZMQ_DIR/licenses"
 test -d "$LICENSE_DIR" || mkdir "$LICENSE_DIR"
-
+SHLIB_EXT=".so"
 if [[ "$(uname)" == "Darwin" ]]; then
+    SHLIB_EXT=".dylib"
     # make sure deployment target is set
     echo "${MACOSX_DEPLOYMENT_TARGET=}"
     test ! -z "${MACOSX_DEPLOYMENT_TARGET}"
@@ -44,6 +45,12 @@ if [[ "$(uname)" == "Darwin" ]]; then
 fi
 
 PREFIX="${ZMQ_PREFIX:-/usr/local}"
+
+if [ -f "$PREFIX/lib/libzmq${SHLIB_EXT}" ]; then
+  echo "using $PREFIX/lib/libzmq${SHLIB_EXT}"
+  exit 0
+fi
+
 # add rpath so auditwheel patches it
 export LDFLAGS="${LDFLAGS} -Wl,-rpath,$PREFIX/lib"
 

zmq/backend/cython/_zmq.py

@@ -57,22 +57,20 @@
     size_t,
     sizeof,
 )
-from cython.cimports.cpython import (
-    PyBytes_AsString,
-    PyBytes_FromStringAndSize,
-    PyBytes_Size,
-    PyErr_CheckSignals,
-)
 from cython.cimports.cpython.buffer import (
     Py_buffer,
     PyBUF_ANY_CONTIGUOUS,
     PyBUF_WRITABLE,
     PyBuffer_Release,
     PyObject_GetBuffer,
 )
+from cython.cimports.cpython.bytes import (
+    PyBytes_AsString,
+    PyBytes_FromStringAndSize,
+    PyBytes_Size,
+)
+from cython.cimports.cpython.exc import PyErr_CheckSignals
 from cython.cimports.libc.errno import EAGAIN, EINTR, ENAMETOOLONG, ENOENT, ENOTSOCK
-
-# cimports require Cython 3
 from cython.cimports.libc.stdint import uint32_t
 from cython.cimports.libc.stdio import fprintf
 from cython.cimports.libc.stdio import stderr as cstderr
@@ -367,10 +365,10 @@ def __init__(
             _check_rc(rc)
         self._failed_init = False
 
-    def __del__(self):
+    def __dealloc__(self):
         if self._failed_init:
             return
-        # This simply decreases the 0MQ ref-count of zmq_msg.
+        # decrease the 0MQ ref-count of zmq_msg
         with nogil:
             rc: C.int = zmq_msg_close(address(self.zmq_msg))
         _check_rc(rc)

zmq/utils/mutex.h

@@ -9,6 +9,8 @@
 
 #pragma once
 
+#include <stdlib.h>
+
 #if defined(_WIN32)
 #  include <windows.h>
 #else