NetBSD ships with strtod_l(3) in <stdlib.h>.
Having strtol_l(3) doesn't imply to have <xlocale.h>.
Generalize inclusion of <locale.h> and <xlocale.h>.
AC_CHECK_HEADERS_ONCE([execinfo.h])
AC_CHECK_HEADERS_ONCE([langinfo.h])
AC_CHECK_HEADERS_ONCE([regex.h pcreposix.h])
+AC_CHECK_HEADERS_ONCE([locale.h xlocale.h])
AM_CONDITIONAL(HAVE_SYS_EVENTFD_H, test "x$ac_cv_header_sys_eventfd_h" = "xyes")
#endif
#ifdef HAVE_STRTOD_L
+#ifdef HAVE_LOCALE_H
#include <locale.h>
+#endif
+#ifdef HAVE_XLOCALE_H
#include <xlocale.h>
#endif
+#endif
#ifdef HAVE_SCHED_H
#include <sched.h>
#endif
#ifdef __APPLE__
-#include <xlocale.h>
#include <mach/mach_init.h>
#include <mach/thread_act.h>
#include <mach/thread_policy.h>