Revert "testsuite: mark jspace as fragile on i386."

This reverts commit 0038d052.

The atomicity bug should be fixed by !11802.

testsuite/tests/driver/j-space/all.T

-test('jspace', [extra_files(['genJspace']), req_target_smp, req_ghc_smp, js_broken(22573),when(arch('i386'), fragile(24261))], makefile_test, ['jspace'])
+test('jspace', [extra_files(['genJspace']), req_target_smp, req_ghc_smp, js_broken(22573)], makefile_test, ['jspace'])