tools: Don't use distutils in configure or Makefile

Python distutils is deprecated and is going to be removed in Python
3.12.  distutils.sysconfig is available as the sysconfig module in
stdlib since Python 2.7 and Python 3.2, so use that directly.

Update the README to reflect that we now depend on Python 2.7.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Javi Merino <javi.merino@cloud.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
[Regen ./configure]
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

README

@@ -50,7 +50,7 @@ provided by your OS distributor:
         - GNU Binutils 2.24 or later
     * POSIX compatible awk
     * Development install of zlib (e.g., zlib-dev)
-    * Development install of Python 2.6 or later (e.g., python-dev)
+    * Development install of Python 2.7 or later (e.g., python-dev)
     * Development install of curses (e.g., libncurses-dev)
     * Development install of openssl (e.g., openssl-dev)
     * Development install of x11 (e.g. xorg-x11-dev)
@@ -180,7 +180,7 @@ Python Runtime Libraries
 
 Various tools, such as pygrub, have the following runtime dependencies:
 
-    * Python 2.6 or later.
+    * Python 2.7 or later.
           URL:    https://www.python.org/
           Debian: python