[yocto] Issue cross-compiling Asterisk 13.16.0

[Chris Trobridge]

I am updating the asterisk recipe to 13.16.0 to fix some security advisories and hit an issue in the configuration script new to me:

config.log:
configure:17599: checking if we have usable eventfd support
configure:17602: error: in `/home/chris/yocto/build/tmp/work/core2-32-poky-linux/asterisk/13.16.0-r0/asterisk-13.16.0':
configure:17604: error: cannot run test program while cross compiling

configure:
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if we have usable eventfd support" >&5
$as_echo_n "checking if we have usable eventfd support... " >&6; }
if test "$cross_compiling" = yes; then :
  { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
as_fn_error $? "cannot run test program while cross compiling
See \`config.log' for more details" "$LINENO" 5; }

configure.ac:
AC_MSG_CHECKING([if we have usable eventfd support])
AC_RUN_IFELSE(
  [AC_LANG_PROGRAM([#include <sys/eventfd.h>],
      [return eventfd(0, EFD_NONBLOCK | EFD_SEMAPHORE) == -1;])],
  AC_MSG_RESULT(yes)
  AC_DEFINE([HAVE_EVENTFD], 1, [Define to 1 if your system supports eventfd and the EFD_NONBLOCK and EFD_SEMAPHORE flags.]),
  AC_MSG_RESULT(no)
)

I can see how this follows through but it's not clear how to fix it.  Thus far I think to avoid the test I need to provide a suitable cached value in a site file.   A bit of searching found "CACHED_CONFIGUREVARS", which appears to do this, but what would the variable name be?

Is this a test I can bypass in this way?

Thanks,
Chris