test: Let Autoconf generate env vars for tests

This simplifies the setup script a lot, and also makes it easier to
run tests independently.

Signed-off-by: Jacques de Laval <jacques@de-laval.se>

test/test.env.in

@@ -0,0 +1,6 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+
+export TESTENV_PATH=/bin:/sbin:"@bindir@":"@sbindir@"
+export FINIT_CONF="@FINIT_CONF@"
+export FINIT_RCSD="@FINIT_RCSD@"