tests: check some remake features with non-GNU make too

tests: check some remake features with non-GNU make too

* tests/acloca14.test ($required): Drop "GNUmake".  This test
works as-is with non-GNU make implementations.
* tests/remake1a.test: Likewise.
* tests/aclocal4.test ($required): Drop "GNUmake".
Modify the test to have it work also with non-GNU make.
* tests/remake5.test: Likewise.
* tests/remake8a.test: Likewise.
* tests/remake8b.test: Likewise.
* tests/remake9a.test: Likewise.
* tests/remake9b.test: Likewise.
* tests/remake9c.test: Likewise.
* tests/remake9d.test: Likewise.
* tests/remake10a.test: Likewise.
* tests/remake10b.test: Likewise.
* tests/remake10c.test: Likewise.
* tests/remake12.test: ($required): Drop "GNUmake".
Adapt the test to make it work also with non-GNU make (if
it supports an "include" directive).