bitbake-dev: Fix a couple of bugs that crept in breaking runtime

Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

bitbake-dev/lib/bb/build.py

@@ -191,7 +191,7 @@ def exec_func(func, d, dirs = None):
         so.close()
         se.close()
 
-        if os.path.getsize(logfile) == 0:
+        if os.path.exists(logfile) and os.path.getsize(logfile) == 0:
             bb.msg.debug(2, bb.msg.domain.Build, "Zero size logfile %s, removing" % logfile)
             os.remove(logfile)