Add basic assembler interface and an x86 backend.

Change-Id: Ia8136bad88f1194c8a247e2af80e486ab88c1e8c
diff --git a/src/logging.h b/src/logging.h
index 2c05382..c1896e9 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -74,6 +74,7 @@
 #endif
 
 #define LOG_INFO LogMessage(__FILE__, __LINE__)
+#define LOG_FATAL LogMessageFatal(__FILE__, __LINE__)
 #define LOG(severity) LOG_ ## severity.stream()
 #define LG LOG(INFO)