Fix [#26207] Render.exe mangles paths in mysterious and awesome ways

Reported by Edwin Amsler

The function for extrapolating the template name with the frame number didn't properly NULL-terminate the
resulting string, this causing broken names and weird paths (if you were lucky - totally unusuable names
detected while stepping through the code).

source/blender/blenlib/intern/path_util.c

@@ -609,6 +609,7 @@ int BLI_path_frame(char *path, int frame, int digits)
 		p= tmp + ch_sta;
 		p += sprintf(p, format, frame);
 		memcpy(p, path + ch_end, strlen(path + ch_end));
+		*(tmp+strlen(path)) = '\0';
 #endif
 		strcpy(path, tmp);
 		return 1;