HTTP/2: improved HPACK integer parsing code readability.

No functional changes.

src/http/v2/ngx_http_v2.c

diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c
index 54458da..5852c99 100644
--- a/src/http/v2/ngx_http_v2.c
+++ b/src/http/v2/ngx_http_v2.c
@@ -2396,8 +2396,8 @@
         return value;
     }
 
-    if (end - p > NGX_HTTP_V2_INT_OCTETS - 1) {
-        end = p + NGX_HTTP_V2_INT_OCTETS - 1;
+    if (end - start > NGX_HTTP_V2_INT_OCTETS) {
+        end = start + NGX_HTTP_V2_INT_OCTETS;
     }
 
     for (shift = 0; p != end; shift += 7) {
@@ -2417,7 +2417,7 @@
         }
     }
 
-    if ((size_t) (end - start) >= NGX_HTTP_V2_INT_OCTETS) {
+    if (end == start + NGX_HTTP_V2_INT_OCTETS) {
         return NGX_DECLINED;
     }