Fix file descriptor leak when opening invalid archives.

Also add -Wunreachable-code to the set of compiler flags, otherwise
noreturn becomes considerably less useful.

bug: https://code.google.com/p/android/issues/detail?id=171099
Change-Id: I9a95d45633c731c7046d4e4a39844d9cebfd1718
diff --git a/fastboot/fastboot.h b/fastboot/fastboot.h
index 1786e49..481c501 100644
--- a/fastboot/fastboot.h
+++ b/fastboot/fastboot.h
@@ -69,7 +69,7 @@
 /* util stuff */
 double now();
 char *mkmsg(const char *fmt, ...);
-void die(const char *fmt, ...);
+__attribute__((__noreturn__)) void die(const char *fmt, ...);
 
 void get_my_path(char *path);