Add dev-qt from an older version of the gentoo repo

Qt5 has been removed, we restore it since we still use it.

dev-qt/qtbase/files/qtbase-6.6.1-forkfd-childstack-size.patch

@@ -0,0 +1,27 @@
+Avoid crash that happens for some users in qsb, qmake, and
+potentially other Qt tools when ran under sandbox leading
+to build failures for qtdeclarative and other packages.
+
+Former fix involved replacing 4096 by SIGSTKSZ but
+bug #918664 shown that this may be insufficient so this
+tries 32k instead.
+
+Update: after https://bugs.gentoo.org/923013 and a fixed
+sandbox been stabilized for some time, it should in theory
+be possible to drop this
+
+https://bugs.gentoo.org/908809
+https://bugs.gentoo.org/908816
+https://bugs.gentoo.org/913493
+https://bugs.gentoo.org/915695
+https://bugs.gentoo.org/918664
+https://codereview.qt-project.org/c/qt/qtbase/+/513140
+--- a/src/3rdparty/forkfd/forkfd_linux.c
++++ b/src/3rdparty/forkfd/forkfd_linux.c
+@@ -158,5 +158,5 @@
+ int system_vforkfd(int flags, pid_t *ppid, int (*childFn)(void *), void *token, int *system)
+ {
+-    __attribute__((aligned(64))) char childStack[SIGSTKSZ];
++    __attribute__((aligned(64))) char childStack[32768];
+     pid_t pid;
+     int pidfd;