Fix regression in ansi.test (failure on AIX 5.3). * tests/ansi.test: Remove redundant hackish check done using a hand-postprocessed Makefile.in. This checs worked by setting the `$(SHELL)' macro on the command line of make, but this is not supported by the AIX 5.3 make implementation. This bug has been lurking for a long time, and was activated by commit v1.11-125-gc1f6cdb "Enable `errexit' shell flag in various tests". Report by Ralf Wildenhues.