tiff/doubles2str: factor out component_len

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/tiff.c

@@ -207,14 +207,15 @@ static char *doubles2str(double *dp, int count, const char *sep)
 {
     int i;
     char *ap, *ap0;
+    int component_len = 15 + strlen(sep);
     if (!sep) sep = ", ";
-    ap = av_malloc((15 + strlen(sep)) * count);
+    ap = av_malloc(component_len * count);
     if (!ap)
         return NULL;
     ap0   = ap;
     ap[0] = '\0';
     for (i = 0; i < count; i++) {
-        int l = snprintf(ap, 15 + strlen(sep), "%f%s", dp[i], sep);
+        int l = snprintf(ap, component_len, "%f%s", dp[i], sep);
         ap += l;
     }
     ap0[strlen(ap0) - strlen(sep)] = '\0';