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/qtwebengine/files/qtwebengine-6.9.0-x11-pixmap-leak.patch

@@ -0,0 +1,43 @@
+Patch status: fixed in Qt 6.9.1
+
+https://bugreports.qt.io/browse/QTBUG-135047
+https://codereview.qt-project.org/c/qt/qtwebengine/+/634033
+--- a/src/core/compositor/native_skia_output_device_opengl.cpp
++++ b/src/core/compositor/native_skia_output_device_opengl.cpp
+@@ -214,9 +214,10 @@
+             glFun->glBindTexture(GL_TEXTURE_2D, 0);
+ 
+-            m_frontBuffer->textureCleanupCallback = [glFun, glxFun, display, glxPixmap,
+-                                                     glTexture]() {
++            m_frontBuffer->textureCleanupCallback = [glFun, glxFun, display, glxPixmap, glTexture,
++                                                     glxHelper, pixmapId]() {
+                 glxFun->glXReleaseTexImageEXT(display, glxPixmap, GLX_FRONT_LEFT_EXT);
+                 glFun->glDeleteTextures(1, &glTexture);
+                 glXDestroyGLXPixmap(display, glxPixmap);
++                glxHelper->freePixmap(pixmapId);
+             };
+         }
+--- a/src/core/ozone/glx_helper.cpp
++++ b/src/core/ozone/glx_helper.cpp
+@@ -101,3 +101,13 @@
+ }
+ 
++void GLXHelper::freePixmap(uint32_t pixmapId) const
++{
++    xcb_void_cookie_t cookie = xcb_free_pixmap_checked(m_connection, pixmapId);
++    xcb_generic_error_t *error = xcb_request_check(m_connection, cookie);
++    if (error) {
++        qWarning("GLX: XCB_FREE_PIXMAP failed with error code: 0x%x", error->error_code);
++        free(error);
++    }
++}
++
+ QT_END_NAMESPACE
+--- a/src/core/ozone/glx_helper.h
++++ b/src/core/ozone/glx_helper.h
+@@ -34,4 +34,5 @@
+     GLXPixmap importBufferAsPixmap(int dmaBufFd, uint32_t size, uint16_t width, uint16_t height,
+                                    uint16_t stride) const;
++    void freePixmap(uint32_t pixmapId) const;
+     bool isDmaBufSupported() const { return m_isDmaBufSupported; }
+