www/qt5-webengine: fix build with clang 14

Fixes compile error:

In file included from gen/third_party/blink/renderer/platform/platform_jumbo_63.cc:8:
./../../../../qtwebengine-everywhere-src-5.15.2/src/3rdparty/chromium/third_party/blink/renderer/platform/text/text_break_iterator_icu.cc:122:15: error: anonymous non-C-compatible type given name for linkage purposes by typedef declaration after its linkage was computed; add a tag name here to establish linkage prior to definition
typedef struct {
              ^
               UTextWithBuffer
./../../../../qtwebengine-everywhere-src-5.15.2/src/3rdparty/chromium/third_party/blink/renderer/platform/text/text_break_iterator_icu.cc:123:3: note: type is not C-compatible due to this member declaration
  DISALLOW_NEW();
  ^~~~~~~~~~~~~~
../../../../qtwebengine-everywhere-src-5.15.2/src/3rdparty/chromium/third_party/blink/renderer/platform/wtf/allocator/allocator.h:40:2: note: expanded from macro 'DISALLOW_NEW'
 public:                                                                      \
 ^~~~~~~
./../../../../qtwebengine-everywhere-src-5.15.2/src/3rdparty/chromium/third_party/blink/renderer/platform/text/text_break_iterator_icu.cc:126:3: note: type is given name 'UTextWithBuffer' for linkage purposes by this typedef declaration
} UTextWithBuffer;
  ^

PR:		261949
Approved by:	adridg (maintainer)
MFH:		2022Q1