libavutil/timer: Fix clang reserved-user-defined-literal

clang errors when compiling with C++11 about needing spaces between
literal and identifier

Signed-off-by: Christopher Degawa <ccom@randomderp.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavutil/timer.h

@@ -87,7 +87,7 @@
         if (((tcount + tskip_count) & (tcount + tskip_count - 1)) == 0) { \
             int i;                                                        \
             av_log(NULL, AV_LOG_ERROR,                                    \
-                   "%7"PRIu64" " FF_TIMER_UNITS " in %s,%8d runs,%7d skips",          \
+                   "%7" PRIu64 " " FF_TIMER_UNITS " in %s,%8d runs,%7d skips",\
                    tsum * 10 / tcount, id, tcount, tskip_count);          \
             for (i = 0; i < 32; i++)                                      \
                 av_log(NULL, AV_LOG_VERBOSE, " %2d", av_log2(2*thistogram[i]));\