* gnu/packages/linux.scm (hotspot): Update to 1.5.1. [arguments]: Set #:qtbase to qtbase. <#:configure-flags>: Pass -DQT6_BUILD=ON. [inputs]: Add ki18n, qtdeclarative and qtsvg. Remove qcustomplot, qtbase-5, qtdeclarative-5, qtquickcontrols2-5, qtsvg-5, qtx11extras. Change-Id: I8daf6b74b662f54b3555035ec7c9395472e8d9a6