aerc: run the full test suite

With 2991ed7a16 ("musl: backport patch to fix fgetws") merged, the
tests of the included filters written in C no longer fail on musl and
can thus be enabled.

srcpkgs/aerc/template

@@ -21,3 +21,7 @@ post_install() {
 	make PREFIX=/usr DESTDIR=${DESTDIR} install
 	vlicense LICENSE
 }
+
+do_check() {
+	make ${makejobs} tests
+}