versioner: refactor to use CompilerInstance directly.

This will make it easier to switch over to a virtual filesystem,
which should drastically improve performance.

This also fixes an issue with warning/error reporting.

Bug: http://b/32748936
Test: python run_tests.py
Change-Id: I2e967acf75db29c95f3a03f4f94cccd22c367ad5
diff --git a/libc/include/sys/signalfd.h b/libc/include/sys/signalfd.h
index a21c57b..79f9490 100644
--- a/libc/include/sys/signalfd.h
+++ b/libc/include/sys/signalfd.h
@@ -29,9 +29,10 @@
 #ifndef _SYS_SIGNALFD_H_
 #define _SYS_SIGNALFD_H_
 
+#include <sys/cdefs.h>
+
 #include <linux/signalfd.h>
 #include <signal.h>
-#include <sys/cdefs.h>
 
 __BEGIN_DECLS