[PATCH] Fix build with -Werror=format-security

Fedora, starting with version 21, will enable this flag in order to limit
potentially insecure uses of format strings. It is required for format strings
to be constant now.
---
Also, you may want to have a look at other patches we use:
See: http://pkgs.fedoraproject.org/cgit/ircp-tray.git/tree/

Thank you!

 src/recvfile.c | 5 ++---
 src/sendfile.c | 6 +++---
 2 files changed, 5 insertions(+), 6 deletions(-)