QRawFont: fix UB (misaligned load) in fontTable()

Found by UBSan:

  qrawfont.cpp:618:60: runtime error: load of misaligned address 0x2acee92a5569 for type 'const quint32', which requires 4 byte alignment

Fix by using MAKE_TAG(), like everywhere else, instead
of a load through a type-punned and misaligned pointer.

Change-Id: I52b88ca05a57f7d8c5e5bce953384de49514079b
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>