Stop using `which` for finding python interpreter

Which is not available in minimal build environments (see #1825 for an
example) so replace it with AC_PATH_PROG.

diff --git a/configure.ac b/configure.ac
index 4aa3af7d5b7eac90318746c262faee717e5d9acd..a1c3303beca22cb7aefd4d9dca4d2d07bc2d09f2 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -3883,14 +3883,12 @@ PATH="$with_python_path"
 
 if test "x$with_python" = "xyes" && test "x$with_python_prog" = "x"
 then
-       AC_MSG_CHECKING([for python])
-       with_python_prog="`which python 2>/dev/null`"
-       if test "x$with_python_prog" = "x"
+       AC_PATH_PROG([PYTHON], [python])
+       if test "x$PYTHON" = "x"
        then
-               AC_MSG_RESULT([not found])
                with_python="no (interpreter not found)"
        else
-               AC_MSG_RESULT([$with_python_prog])
+               with_python_prog="$PYTHON"
        fi
 fi