scripts: Add script to split kernel config files

This script is slightly modified from the ChromiumOS splitconfig

It takes a number of kernel config files and prints the common
on specific kernel config options to seperate files.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

scripts/kconfig-split.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python
+
+# This is a slightly modified version of ChromiumOS' splitconfig
+# https://chromium.googlesource.com/chromiumos/third_party/kernel/+/stabilize-5899.B-chromeos-3.14/chromeos/scripts/splitconfig
+
+"""See this page for more details:
+http://dev.chromium.org/chromium-os/how-tos-and-troubleshooting/kernel-configuration
+"""
+import os
+import re
+import sys
+
+allconfigs = {}
+
+# Parse config files
+for config in sys.argv[1:]:
+
+    allconfigs[config] = set()
+
+    for line in open(config):
+        m = re.match("#*\s*CONFIG_(\w+)[\s=](.*)$", line)
+        if not m:
+            continue
+        option, value = m.groups()
+        allconfigs[config].add((option, value))
+
+# Split out common config options
+common = allconfigs.values()[0].copy()
+for config in allconfigs.keys():
+    common &= allconfigs[config]
+for config in allconfigs.keys():
+    allconfigs[config] -= common
+
+allconfigs["common"] = common
+
+# Generate new splitconfigs
+for config in allconfigs.keys():
+    f = open("split-" + config, "w")
+    for option, value in sorted(list(allconfigs[config])):
+        if value == "is not set":
+            print >>f, "# CONFIG_%s %s" % (option, value)
+        else:
+            print >>f, "CONFIG_%s=%s" % (option, value)
+    f.close()