HPack: fix a Yoda Condition

Putting the variable on the LHS of a relational operation makes the
expression easier to read. In this case, we find that the whole
expression is nonsensical as an overflow protection, because if
name.size() + value.size() overflows, the result will exactly _not_
be > max() - 32, because UB will have happened.

To be fixed in a follow-up commit.

As a drive-by, add parentheses around the RHS.

Pick-to: 6.5 6.2 5.15
Change-Id: I35ce598884c37c51b74756b3bd2734b9aad63c09
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
(cherry picked from commit 658607a34ead214fbacbc2cca44915655c318ea9)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 4f7efd41740107f90960116700e3134f5e433867)

src/network/access/http2/hpacktable.cpp

@@ -27,7 +27,7 @@ HeaderSize entry_size(QByteArrayView name, QByteArrayView value)
     // 32 octets of overhead."
 
     const unsigned sum = unsigned(name.size() + value.size());
-    if (std::numeric_limits<unsigned>::max() - 32 < sum)
+    if (sum > (std::numeric_limits<unsigned>::max() - 32))
         return HeaderSize();
     return HeaderSize(true, quint32(sum + 32));
 }