Fix disappearing unit fields in Spicy type export.

When a Spicy unit type was used in an EVT event definition, it could
end up being cleared out at the time the logic for `export` got to see it.

Closes #3083.

Note: This needs backporting to the legacy plugin.

src/spicy/spicyz/glue-compiler.cc

@@ -985,7 +985,7 @@ bool GlueCompiler::PopulateEvents() {
             }
         }
 
-        ev.unit_type = std::move(uinfo.type.as<::spicy::type::Unit>());
+        ev.unit_type = uinfo.type.as<::spicy::type::Unit>();
         ev.unit_module_id = uinfo.module_id;
         ev.unit_module_path = uinfo.module_path;
 

testing/btest/Baseline/spicy.export-type-e2e/output

@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+[x=71]
+[x=72]

testing/btest/spicy/export-type-e2e.zeek

@@ -0,0 +1,31 @@
+# @TEST-REQUIRES: have-spicy
+#
+# @TEST-EXEC: spicyz -do export.hlto export.spicy export.evt
+# @TEST-EXEC: zeek -Cr $TRACES/http/pipelined-requests.trace export.hlto %INPUT >>output
+# @TEST-EXEC: test '!' -e reporter.log
+# @TEST-EXEC: btest-diff output
+#
+# @TEST-DOC: Test type export end-to-end, with access from the Zeek side. Regression test for #3083.
+
+# @TEST-START-FILE export.spicy
+module foo;
+
+public type X = unit {
+    x: uint8;
+};
+# @TEST-END-FILE
+
+# @TEST-START-FILE export.evt
+import foo;
+
+protocol analyzer FOO over TCP:
+    parse with foo::X,
+    port 1/tcp-40000/tcp;
+
+export foo::X;
+
+on foo::X -> event foo::hello(self);
+# @TEST-END-FILE
+
+event foo::hello(x: foo::X)
+	{ print x; }