Fix python path selection bug in autoconf

This fixes the problem of generating invalid Makefiles when more than
one python installation is found.

m4/ax_python.m4

@@ -58,13 +58,13 @@
 AC_DEFUN([AX_PYTHON],
 [AC_MSG_CHECKING(for python build information)
 AC_MSG_RESULT([])
-for python in python2.5 python2.4 python2.3 python2.2 python2.1 python; do
+for python in python2.6 python2.5 python2.4 python2.3 python2.2 python2.1 python; do
 AC_CHECK_PROGS(PYTHON_BIN, [$python])
 ax_python_bin=$PYTHON_BIN
 if test x$ax_python_bin != x; then
    AC_CHECK_LIB($ax_python_bin, main, ax_python_lib=$ax_python_bin, ax_python_lib=no)
    AC_CHECK_HEADER([$ax_python_bin/Python.h],
-   [[ax_python_header=`locate $ax_python_bin/Python.h | sed -e s,/Python.h,,`]],
+   [[ax_python_header=`locate -n 1 $ax_python_bin/Python.h | sed -e s,/Python.h,,`]],
    ax_python_header=no)
    if test "$ax_python_lib" != "no"; then
      if test "$ax_python_header" != "no"; then