httpd: fix compile failure if !FEATURE_HTTPD_RANGES

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/httpd.c b/networking/httpd.c
index 1ba1d10..3304516 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -1880,9 +1880,13 @@
 #if ENABLE_FEATURE_USE_SENDFILE
 	{
 		off_t offset;
+# if ENABLE_FEATURE_HTTPD_RANGES
 		if (range_start < 0)
 			range_start = 0;
 		offset = range_start;
+# else
+		offset = 0;
+# endif
 		while (1) {
 			/* sz is rounded down to 64k */
 			ssize_t sz = MAXINT(ssize_t) - 0xffff;