crossdev: fail eval when multilib.eclass sourcing fails

Before the change failure to source 'multilib.eclass' resuled in
a fallback mode to be used instead of hard failure.

It was caused by two expansion layers of 'eval $(...)'.

After the change falure to source 'mmultilib.eclass' hard fails early:

```
$ PORTAGE_CONFIGROOT=$(pwd)/foo EPREFIX=$(pwd)/foo PORT_LOGDIR=$(pwd)/foo ./crossdev -t mmix -P -p
 * error: : EAPI 0 not supported
 *
 * If you file a bug, please attach the following logfiles:
 * /home/slyfox/dev/git/crossdev/foo/cross--info.log
 *
 * error: could not load multilib settings for 'HCHOST'
 *
 * If you file a bug, please attach the following logfiles:
 * /home/slyfox/dev/git/crossdev/foo/cross-mmix-info.log
```

Reported-by: Marco Scardovi (scardracs)
Bug: https://bugs.gentoo.org/797367
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/crossdev b/crossdev
index 1a2b030..619603f 100755
--- a/crossdev
+++ b/crossdev
@@ -968,6 +968,9 @@ fi
 # parse multilib settings until profiles are sane
 load_multilib_env() {
 	local var=$1
+	# TODO: avoid eval+subshell and use subshell only. It will make error
+	# handling simpler.
+	local eval_result=failed
 	eval $(
 	# see what target to parse
 	CTARGET=${!var}
@@ -1016,7 +1019,9 @@ load_multilib_env() {
 			echo ${_v}=\'${!d}\'
 		done
 	done
+	echo "eval_result='succeeded'"
 	)
+	[[ $eval_result = succeeded ]] || die "could not load multilib settings for '${var}'"
 }
 # Load settings for the host.
 MULTILIB_ABIS=${HOST_ABI} load_multilib_env HCHOST