build fixes for GCC 11

Origin: upstream, commits:
 https://code.qt.io/cgit/qt/qtdeclarative.git/commit/?id=eb6525f126f680f9
 https://code.qt.io/cgit/qt/qtdeclarative.git/commit/?id=367293b18ab0d0a0
 https://code.qt.io/cgit/qt/qtdeclarative.git/commit/?id=db58b8518e157b76
Last-Update: 2021-08-18

Gbp-Pq: Name gcc_11.patch

qtdeclarative-opensource-src (5.15.4+dfsg-3) unstable; urgency=medium

  * Upload to unstable.

[dgit import unpatched qtdeclarative-opensource-src 5.15.4+dfsg-3]

Import qtdeclarative-opensource-src_5.15.4+dfsg-3.debian.tar.xz

[dgit import tarball qtdeclarative-opensource-src 5.15.4+dfsg-3 qtdeclarative-opensource-src_5.15.4+dfsg-3.debian.tar.xz]

Import qtdeclarative-opensource-src_5.15.4+dfsg.orig.tar.xz

[dgit import orig qtdeclarative-opensource-src_5.15.4+dfsg.orig.tar.xz]