configurator: Enable running configurator in wrapper

Since the probing binaries compiled by the configurator needs to run on
the host machine we provide a variable CONFIGURATOR_WRAPPER that can be
set to anything that you want to wrap the calls with.

One example is `qemu-aarch64-static`.

configure

@@ -230,7 +230,7 @@ fi
 require 'python3-mako' "You need the mako module for python3: see doc/INSTALL.md" python3 -c 'import mako'
 
 rm -f $CONFIG_VAR_FILE.$$
-$CONFIGURATOR --extra-tests --autotools-style --var-file=$CONFIG_VAR_FILE.$$ --header-file=$CONFIG_HEADER --configurator-cc="$CONFIGURATOR_CC" "$CC" ${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS -I/usr/local/include -L/usr/local/lib <<EOF
+$CONFIGURATOR --extra-tests --autotools-style --var-file=$CONFIG_VAR_FILE.$$ --header-file=$CONFIG_HEADER --configurator-cc="$CONFIGURATOR_CC" --wrapper="$CONFIGURATOR_WRAPPER" "$CC" ${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS -I/usr/local/include -L/usr/local/lib <<EOF
 var=HAVE_GOOD_LIBSODIUM
 desc=libsodium with IETF chacha20 variants
 style=DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE