Fix misc. issues reported by Coverity.

Some uninitialized values, a possible null pointer dereference, and
time-of-check-time-of-use on reading random seed file.

src/PolicyFile.cc

@@ -86,6 +86,7 @@ bool LoadPolicyFileText(const char* policy_filename)
 		char buf[256];
 		strerror_r(errno, buf, sizeof(buf));
 		reporter->Error("fstat failed on %s: %s", policy_filename, buf);
+		fclose(f);
 		return false;
 		}