Script to generate compile_commands.json from compile_flags.txt

This enables background index for a compile_flags.txt driven project.
(We should really have a better solution for this)

scripts/compile_flags_json.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+import os, sys, json
+
+EXTS = ('.c','.C','.cpp','.cc','.cxx','.m','.mm'
+        '.h','.H','.hpp','.hh','.hxx')
+
+input = sys.argv[1] if len(sys.argv) > 1 else 'compile_flags.txt'
+driver = sys.argv[2] if len(sys.argv) > 2 else 'clang'
+with open(input) as f:
+    flags = [line.strip() for line in f]
+
+dir = os.path.dirname(os.path.abspath(input))
+
+entries = []
+
+for root, dirs, files in os.walk(dir):
+    for file in files:
+        ext = os.path.splitext(file)[1]
+        if ext in EXTS:
+            entries.append({
+                'directory': dir,
+                'file': os.path.join(dir, file),
+                'arguments': [driver] + flags + [os.path.join(dir, file)]})
+
+with open(os.path.join(dir, 'compile_commands.json'), 'w') as file:
+    json.dump(entries, file, indent=2)
+