sh testsuite: add tests for exitcode on failure to exec

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-misc/exitcode_EACCES.right b/shell/hush_test/hush-misc/exitcode_EACCES.right
new file mode 100644
index 0000000..a80d551
--- /dev/null
+++ b/shell/hush_test/hush-misc/exitcode_EACCES.right
@@ -0,0 +1,2 @@
+hush: can't execute './': Permission denied
+126