Switch kernel header parsing to python libclang

Replace the tokenizer in cpp.py with libclang.

Bug: 18937958
Change-Id: I27630904c6d2849418cd5ca3d3c612ec3078686d
diff --git a/libc/kernel/uapi/linux/ashmem.h b/libc/kernel/uapi/linux/ashmem.h
index a1f8760..4711ef3 100644
--- a/libc/kernel/uapi/linux/ashmem.h
+++ b/libc/kernel/uapi/linux/ashmem.h
@@ -28,8 +28,8 @@
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define ASHMEM_IS_PINNED 1
 struct ashmem_pin {
- __u32 offset;
- __u32 len;
+  __u32 offset;
+  __u32 len;
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 };
 #define __ASHMEMIOC 0x77