[FFmpeg-cvslog] avutil/log: fix zero length gnu_printf format string warning

[Ganesh Ajjanagadde]

ffmpeg | branch: release/2.7 | Ganesh Ajjanagadde <gajjanagadde at gmail.com> | Thu Sep 17 08:11:39 2015 -0400| [abd20c20576324c50336dedb9a21856036dc11d0] | committer: Michael Niedermayer

avutil/log: fix zero length gnu_printf format string warning

This should fix warning reported by fate client:
http://fate.ffmpeg.org/report.cgi?time=20150917113121&slot=x86_32-linux-gnu-gcc-4.5.1-have_6regs.
Untested.

Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 63cdb6e4a59e296e27a78ac08f15500b42cd27fc)

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=abd20c20576324c50336dedb9a21856036dc11d0
---

 libavutil/log.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavutil/log.c b/libavutil/log.c
index b2bc65c..4583519 100644
--- a/libavutil/log.c
+++ b/libavutil/log.c
@@ -343,7 +343,7 @@ void av_log_default_callback(void* ptr, int level, const char* fmt, va_list vl)
 
 #if CONFIG_VALGRIND_BACKTRACE
     if (level <= BACKTRACE_LOGLEVEL)
-        VALGRIND_PRINTF_BACKTRACE("");
+        VALGRIND_PRINTF_BACKTRACE("%s", "");
 #endif
 end:
     av_bprint_finalize(part+3, NULL);