sysutils/qdirstat: fix build on armv7

The operator << of the LogStream class is used to output numerical
values among other things. The port tries to output a value of type
unsigned long long on armv7, while presumably not doing so on other
platforms. Add an overload for unsigned long long to fix the build.

Approved by: portmgr (build fix blanket)
MFH: 2026Q1

(cherry picked from commit 09d59b2140bc16c125dbee5e007d0766c1aaa63d)