autoconf: Add support for setting PYTHON_PATH or NO_PYTHON

This patch adds support for setting either PYTHON_PATH or NO_PYTHON to
autoconf generated ./configure script via --with-python=PATH (sets
PYTHON_PATH) or --without-python (sets NO_PYTHON).  Autodetect
PYTHON_PATH via AC_PATH_PROGS.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

configure.ac

@@ -103,6 +103,18 @@ AC_MSG_NOTICE([CHECKS for programs])
 #
 GIT_ARG_SET_PATH(shell)
 GIT_ARG_SET_PATH(perl)
+AC_ARG_WITH(python,[AS_HELP_STRING([--with-python=PATH], [provide PATH to python])
+AS_HELP_STRING([--no-python], [don't use python scripts])],
+ [if test "$withval" = "no"; then \
+    NO_PYTHON=YesPlease; \
+  elif test "$withval" != "yes"; then \
+    PYTHON_PATH=$withval; \
+  fi; \
+ ])
+AC_SUBST(NO_PYTHON)
+AC_SUBST(PYTHON_PATH)
+
+
 #
 # Define NO_PYTHON if you want to lose all benefits of the recursive merge.
 # Define PYTHON_PATH to provide path to Python.
@@ -110,6 +122,16 @@ AC_PROG_CC
 #AC_PROG_INSTALL		# needs install-sh or install.sh in sources
 AC_CHECK_TOOL(AR, ar, :)
 AC_CHECK_PROGS(TAR, [gtar tar])
+if test -z "$NO_PYTHON"; then
+	AC_PATH_PROGS(PYTHON_PATH, [python2.4 python2.3 python2 python])
+	if test -n "$PYTHON_PATH"; then
+		GIT_CONF_APPEND_LINE([PYTHON_PATH=@PYTHON_PATH@])
+	else
+		GIT_CONF_APPEND_LINE([NO_PYTHON=@NO_PYTHON@])
+	fi
+else
+	GIT_CONF_APPEND_LINE([NO_PYTHON=@NO_PYTHON@])
+fi
 
 
 ## Checks for libraries.