tests: tweak and improve tests on "Simple Tests" driver * tests/check.test: Make grepping of generated Makefile.in slightly stricter. Add trailing `:' command. * tests/check2.test: Ensure verbose printing of captured make output. Make grepping of generated Makefile.in and of make output stricter. Add trailing `:' command. * tests/check3.test: Likewise. Also, fix minor error in a comment. * tests/check4.test: Stricter grepping of make output. Use `using_gmake' subroutine instead of copy&paste from defs.in to determine whether $MAKE is GNU make. Add a trailing `:' command. * tests/check6.test: Add trailing `:' command. * tests/check10.test: Prefer redirection `>' over `>>' when creating new files. Ensure verbose printing of captured make output. * tests/check11.test: Likewise. * tests/check7.test: Likewise. Make grepping of make output stricter. Prefer "make distcheck" over a simple "make check" in a VPATH build. Add trailing `:' command. (a.c): Format following GNU coding standards. (Makefile.am): Explicitly declare target `print-xfail-tests' as PHONY. Distribute $(check_SCRIPTS), for distcheck. * tests/parallel-tests.test: Prefer redirection `>' over `>>' when creating new files. * tests/parallel-tests2.test: Likewise. * tests/parallel-tests9.test: Likewise. * tests/parallel-tests8.test: Likewise. Make grepping of automake stderr stricter. * tests/check8.test: Likewise. Make formatting of created *.c files more consistent with GNU Coding Standards. * tests/check-subst-prog.test (configure.in): Break overly long lines. (pass-prog.c, xfail-prog.c): Format them more consistently with GNU Coding Standards. * tests/parallel-tests3.test: Use a shorter and clearer skip message. Use the `unindent' subroutine to improve readability of indented loop bodies. Simplify the hack used to please maintainer-check. * tests/parallel-tests5.test: Make formatting of created *.c files more consistent with GNU Coding Standards. Use the `unindent' subroutine to improve readability of indented loop bodies. * tests/parallel-tests10.test: Add blank line, for clarity. Prefer trailing `:' over trailing `Exit 0', for consistency with other tests.