configure: require python mako module

It is now a hard dependency because of the autogeneration of
format pack and unpack functions.

Update the documentation to reflect this change.

v2:
- Inline python script in m4 file and use PYTHON2

v3:

- Remove semicolons and quotes and change coding style
- Add Ilia Mirkin suggestion to use Python's split functionality.
- Use AX_CHECK_PYTHON_MAKO_MODULE name.
- Change to MIT license

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
diff --git a/configure.ac b/configure.ac
index c8723ef..d4cf4b8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -76,6 +76,8 @@
     AC_SUBST(INDENT_FLAGS, '-i4 -nut -br -brs -npcs -ce -TGLubyte -TGLbyte -TBool')
 fi
 
+AX_CHECK_PYTHON_MAKO_MODULE(0.7.3)
+
 AC_PROG_INSTALL
 
 dnl We need a POSIX shell for parts of the build. Assume we have one