Always distribute test/hs/htest.hs

If in the original configure, haskell-tests are disabled,
test/hs/htest.hs will not be a needed dependency, hence it
will not automatically end up in the distribution tar ball.
Add the file to EXTRA_DIST in this case.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

Makefile.am

@@ -730,6 +730,8 @@ HS_DEFAULT_PROGS = \
 
 if HTEST
 HS_DEFAULT_PROGS += test/hs/htest
+else
+EXTRA_DIST += test/hs/htest.hs
 endif
 
 HS_ALL_PROGS = $(HS_DEFAULT_PROGS) $(HS_MYEXECLIB_PROGS)