wasm: fix link failure in QWebSocket

doClose() was added inside the #ifndef Q_OS_WASM block, but its caller
processError() is compiled unconditionally, leaving the symbol undefined.

Move doClose() out of the block. It is still never reached on wasm:
m_pSocket is null, processError() and other related methods are never
called.

Amends f2d9ebfa602b9b5a203317db1eb8b4e4c3560244

Pick-to: 6.12 6.12.0
Fixes: QTBUG-150785
Change-Id: I7de0136707dba5a233a857a9a8feec9037571d97
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>