build: update build instructions for Qt6 on Debian/Ubuntu

Also add support for the QCustomPlot library name used on Debian.

Author: erijo

HACKING.md

@@ -62,27 +62,22 @@ As of now, you will need the following dependencies to build this project:
 ### On Debian/Ubuntu
 
 ```bash
-add-apt-repository ppa:kubuntu-ppa/backports
 apt-get update
+
+# For Qt5
 apt-get install libkf5threadweaver-dev libkf5i18n-dev libkf5configwidgets-dev libkf5syntaxhighlighting-dev \
     libkf5coreaddons-dev libkf5itemviews-dev libkf5itemmodels-dev libkf5kio-dev libkf5parts-dev \
     libkf5solid-dev libkf5windowsystem-dev libkf5notifications-dev libkf5iconthemes-dev libelf-dev \
     libdw-dev cmake extra-cmake-modules gettext libqt5svg5-dev
-```
-
-Note: Ubuntu 20.04 does not provide the minimal version of QT, if you use this old Ubuntu version then
-you'd need to _additionally_ install it from a version outside of the distro repository.
-The automatic builds via GitHub actions [use the following][Ubuntu2004Script] for that:
 
-```bash
-    sudo add-apt-repository ppa:beineri/opt-qt-5.15.4-focal
-    sudo apt-get update
-    sudo apt-get install -y qt515base qt515svg qt515x11extras \
-        libqt5x11extras5-dev   # this one is optional for Hotspot, but required for KDDockWidgets
+# For Qt6 (-DQT6_BUILD=ON)
+apt-get install libkf6threadweaver-dev libkf6i18n-dev libkf6configwidgets-dev libkf6syntaxhighlighting-dev \
+    libkf6coreaddons-dev libkf6itemviews-dev libkf6itemmodels-dev libkf6kio-dev libkf6parts-dev \
+    libkf6solid-dev libkf6windowsystem-dev libkf6notifications-dev libkf6iconthemes-dev libelf-dev \
+    libdw-dev libdwarf-dev libdebuginfod-dev cmake extra-cmake-modules qt6-svg-dev libzstd-dev \
+    libkddockwidgets-qt6-dev kgraphviewer-dev libqcustomplot-dev
 ```
 
-[Ubuntu2004Script]:https://github.com/KDAB/hotspot/blob/master/scripts/compile-test/BaseUbuntu20.04
-
 ### On Fedora
 
 ```bash

cmake/FindQCustomPlot.cmake

@@ -30,7 +30,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-find_library(QCustomPlot_LIBRARY NAMES qcustomplot-qt${QT_MAJOR_VERSION} qcustomplot)
+find_library(QCustomPlot_LIBRARY NAMES qcustomplot-qt${QT_MAJOR_VERSION} qcustomplot QCustomPlotQt${QT_MAJOR_VERSION})
 set(QCustomPlot_LIBRARIES "${QCustomPlot_LIBRARY}")
 
 find_path(QCustomPlot_INCLUDE_DIR NAMES qcustomplot.h)