configure: fix detection of POSIX shell to work in a VPATH build

* configure.ac: When checking whether "test -e" works, use 'config.log',
not 'configure', as the witness file, because the latter does not exist
in the current directory during a VPATH build.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --git a/configure.ac b/configure.ac
index 8d6afc8..7d30762 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -325,7 +325,7 @@ AC_DEFUN([_AM_CHECK_CANDIDATE_SHELL],
 
     _AM_CHECK_SHELL_FEATURE([$1],
       [supports "test -e"],
-      [test -e configure && test -e . && test ! -e nonesuch],
+      [test -e config.log && test -e . && test ! -e nonesuch],
       [], [am_score=1; break])
 
     break