Drop obsolete --without-spdylay configure argument

This was dropped by upstream several years ago, and so generates
a warning in build logs today.

nghttp2.spec

@@ -53,8 +53,7 @@ sed -e '1 s|^#!/.*python|&3|' -i script/fetch-ocsp-response
     --disable-hpack-tools                   \
     --disable-python-bindings               \
     --disable-static                        \
-    --with-libxml2                          \
-    --without-spdylay
+    --with-libxml2
 
 # avoid using rpath
 sed -i libtool                              \