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/asm-generic/poll.h b/libc/kernel/uapi/asm-generic/poll.h
index 7faa0b8..4137abb 100644
--- a/libc/kernel/uapi/asm-generic/poll.h
+++ b/libc/kernel/uapi/asm-generic/poll.h
@@ -51,9 +51,9 @@
 #define POLL_BUSY_LOOP 0x8000
 struct pollfd {
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
- int fd;
- short events;
- short revents;
+  int fd;
+  short events;
+  short revents;
 };
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #endif