[REG 6.2.3 -> 6.3.0] QGuiApplication leaks memory

1. Configure qtbase with "-sanitize address" and build it.
2. Build the attached project.

   qt-cmake /tmp/report/ && cmake --build .
   

   It only contains a minimal QGuiApplication:

   int main(int argc, char *argv[]) {
       QGuiApplication qga(argc, argv);
       return 0;
   }
   

3. Run the resulting binary:

   ./report
   

   ASAN will report a memory leak:

   qtrob@rob-desktop:/tmp/minimize$ ./report
   
   =================================================================
   ==96478==ERROR: LeakSanitizer: detected memory leaks
   
   Direct leak of 60 byte(s) in 1 object(s) allocated from:
       #0 0x4b446d in malloc (/tmp/minimize/report+0x4b446d)
       #1 0x7fafcd81e0c5  (/usr/lib/x86_64-linux-gnu/libxcb.so.1+0xe0c5)
   
   SUMMARY: AddressSanitizer: 60 byte(s) leaked in 1 allocation(s).
   

Qt 6.2.3 does not leak memory in this situation.