www/webkit2-gtk3: fix build with lld 17

Building www/webkit2-gtk3 with lld 17 results in the following link
errors:

  ld: error: version script assignment of 'global' to symbol 'bmalloc::PerThreadStorage<bmalloc::PerHeapKind<bmalloc::Cache> >::s_didInitialize' failed: symbol not defined
  ld: error: version script assignment of 'global' to symbol 'bmalloc::PerThreadStorage<bmalloc::PerHeapKind<bmalloc::Cache> >::s_key' failed: symbol not defined
  ld: error: version script assignment of 'global' to symbol 'bmalloc::vmPageSize()::cached' failed: symbol not defined

The mentioned symbols are no longer external, and have been removed in
upstream commits:

https://github.com/WebKit/WebKit/commit/655e1bb394f423d6c15de98f5874ab181076d016
https://github.com/WebKit/WebKit/commit/a1c80bec178456c109a62723ff937405cdb35b6b

Since the former does not apply cleanly due to edits in the ChangeLog,
merge the functional changes in a single port patch file.

PR:		274677
Approved by:	gnome (blanket)
MFH:		2023Q4