(read_makefile): Don't mark makefiles as precious. Just like other

targets, they can be left inconsistent and in need of remaking by aborted
commands.

read.c

@@ -331,7 +331,6 @@ read_makefile (filename, flags)
 	deps->file->dontcare = 1;
     }
   filename = deps->file->name;
-  deps->file->precious = 1;
   deps->changed = flags;
   deps = 0;