tests: Support semihosted environment.
* Makefile.am (check-all): Add EXEEXT. * agent/all-tests.scm: Append EXEEXT. * common/all-tests.scm: Likewise. * g10/all-tests.scm: Likewise. * g13/all-tests.scm: Likewise.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>