Log Message:
PC6001VX: update to 4.2.7.

This version includes a fix of SIGSEGV on startup issue with Qt 6.7.1,
by using Qt/SingleApplication 3.4.1 (the previous PC6001VX 4.2.4 with
SingleApplication 3.3.1 fails with Qt 6.7.1).

Upstream changes:
 http://eighttails.seesaa.net/article/503733599.html
 http://eighttails.seesaa.net/article/503611168.html
 http://eighttails.seesaa.net/article/501854573.html

4.2.7
* Merged upstream PC6001V version 2.1.3.
* Updated PC-6001 compatible basic ROMs to 0.8.

4.2.6
* Updated PC-6001mk2/6601 compatible basic ROMs to 0.5.1.
* Compatible with FFmpeg7 (currently buildable with versions 5, 6, and 7)
* (Android)Fixed an issue where the screen layout may be corrupted when
  restarting.

4.2.5
* Fixed screen layout sometimes not updating when enabling/disabling
  virtual keyboard.
* Fixed an issue where the menu appearance position during touch
  operation was incorrect.