Remove depends reference to unknown fix_qt_pkgconfig.patch

[dannylee71]

There is no such .patch file under depends/patches/qt/, and unless I'm mistaken there's no record of there being such a patch before either.

This issue was found trying to follow the build instructions in README.md, and is seen during the step:

$ cd depends && make -j4 BASE_CACHE=$(pwd)/deps-cache SOURCES_PATH=$(pwd)/deps-cache/sources/