Fix build with GCC 4.7

GCC 4.7 actually digs into try_open() and find variable "fname"
isn't initialized in all paths leading to its use at free(fname),
but not smart enough to know that the value of fname doesn't matter
when fd < 0

Initialize fname at definition before GCC gets smarter.

Change-Id: I3bc5b52b3a13e5f4ec49ea0c9627bb0661b11f8a