tests: run tests for each supported personality

tests: run tests for each supported personality

When strace supports more than one personality, run test suite
for each personality supported by the host system.

* bootstrap: Create tests-m32 and tests-mx32 subtrees from tests.
* configure.ac: Check for -m32 and -mx32 runtime support.
(AC_CONFIG_FILES): Add tests-m32/Makefile and tests-mx32/Makefile.
* Makefile.am [HAVE_M32_RUNTIME] (TESTS_M32): Define.
[HAVE_MX32_RUNTIME] (TESTS_MX32): Define.
(SUBDIRS): Add $(TESTS_M32) $(TESTS_MX32).
* .gitignore: Add /tests-m32 and /tests-mx32.