tests: new variable $am_testaux_builddir And a related fix that solves a spurious testsuite failures in VPATH builds. * t/ax/test-defs.in ($am_testaux_builddir): New, counterpart of $am_testaux_srcdir, but pointing inside the build directory. * t/self-check-shell-no-trail-bslash.sh: Use $am_testaux_builddir, not $am_testaux_srcdir, when fetching the 'shell-no-trail-bslash' script. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>