configure: remove unnecessary check

All calls to probe_target_compiler are conditioned on
some "have_target" invocation, or inside a loop on target_list.
Therefore there is no issue with building unnecessary
firmware images and tests.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -1324,13 +1324,6 @@ probe_target_compiler() {
   container_cross_ranlib=
   container_cross_strip=
 
-  # We shall skip configuring the target compiler if the user didn't
-  # bother enabling an appropriate guest. This avoids building
-  # extraneous firmware images and tests.
-  if test "${target_list#*$1}" = "$1"; then
-      return 1
-  fi
-
   target_arch=${1%%-*}
   case $target_arch in
     aarch64) container_hosts="x86_64 aarch64" ;;