--- configure.ac.orig	2026-09-09 00:44:04 UTC
+++ configure.ac
@@ -122,7 +122,38 @@ AC_FUNC_STRERROR_R
 AC_C_RESTRICT
 AC_FUNC_STRERROR_R
 
-AC_PATH_TOOL([PKG_CONFIG], [pkg-config], [pkg-config])
+PKG_PROG_PKG_CONFIG
+
+dnl Float word order can differ from integer endianness on some ABIs.
+dnl Prefer Autoconf's macro if available; otherwise fall back to autoconf-archive.
+m4_ifdef([AC_C_FLOAT_WORDS_BIGENDIAN],
+         [AC_C_FLOAT_WORDS_BIGENDIAN],
+         [m4_ifdef([AX_C_FLOAT_WORDS_BIGENDIAN],
+                   [AX_C_FLOAT_WORDS_BIGENDIAN],
+                   [AC_MSG_ERROR([need AC_C_FLOAT_WORDS_BIGENDIAN or AX_C_FLOAT_WORDS_BIGENDIAN])])])
+
+AC_CHECK_HEADERS([sys/eventfd.h sys/timerfd.h])
+AC_CHECK_HEADERS([netinet/in.h arpa/inet.h])
+
+dnl brk()/sbrk() detection itself is performed by config/m4/ucm.m4.
+dnl Keep a common feature define for FreeBSD UCM compatibility code.
+AS_IF([test "x$ac_cv_func_brk" = "xyes" && test "x$ac_cv_func_sbrk" = "xyes"],
+      [have_brk_sbrk=yes],
+      [have_brk_sbrk=no])
+
+AM_CONDITIONAL([HAVE_BRK_SBRK],
+               [test "x$have_brk_sbrk" = "xyes"])
+
+AS_IF([test "x$have_brk_sbrk" = "xyes"],
+      [AC_DEFINE([HAVE_BRK_SBRK], [1],
+                 [Define if both brk() and sbrk() are available])])
+
+case "$host_os" in
+  freebsd*) build_gtest=no ;;
+  *)        build_gtest=yes ;;
+esac
+AM_CONDITIONAL([BUILD_GTEST],
+               [test "x$build_gtest" = xyes])
 
 AS_IF([test "x$enable_module_deepbind" = xyes],
       [AC_CHECK_DECLS([RTLD_DEEPBIND],