Restore Debian (Ubuntu) build and do not use precompiled libraries for Linux

.appveyor.yml

@@ -28,7 +28,7 @@ environment:
       CMAKE_CUSTOM_OPTIONS: "-DCMAKE_BUILD_TYPE=Release \
                              -DARCH_OPT=nehalem \
                              -DDEBUG_OUTPUT=ON \
-                             -DENABLE_EXTERNAL_LIBRARIES=AUTO \
+                             -DENABLE_EXTERNAL_LIBRARIES=ON \
                              -DBUILD_SERVER=OFF"
     - TARGET: ubuntu2204docker
       APPVEYOR_BUILD_WORKER_CLOUD: nasrock

debian/rules

@@ -3,7 +3,7 @@
 	dh $@ --parallel --buildsystem=cmake+ninja
 
 override_dh_auto_configure:
-	dh_auto_configure -- -DARCH_OPT=nehalem -DENABLE_EXTERNAL_LIBRARIES=AUTO -DDEBUG_OUTPUT=ON -DBUILD_SERVER=OFF
+	dh_auto_configure -- -DARCH_OPT=nehalem -DENABLE_EXTERNAL_LIBRARIES=ON -DDEBUG_OUTPUT=ON -DBUILD_SERVER=OFF
 
 override_dh_auto_test:
 	echo "Skipping test step"

external/CMakeLists.txt

@@ -201,8 +201,7 @@ endif (AUTO_EXTERNAL_LIBRARIES)
 
 # Some of the following projects are currently built only for MacOS
 # For WIN32, we use precompiled versions from sdrangel-windows-libraries
-# For LINUX, we require system pacakges to be installed
-if (APPLE)
+if (APPLE OR LINUX)
     set(USE_PRECOMPILED_LIBS FALSE)
 else()
     set(USE_PRECOMPILED_LIBS TRUE)
@@ -1478,4 +1477,3 @@ endif (WIN32 OR APPLE)
 
 # Set CACHE so variable is visible in cpack CMakeFile
 set(MACOS_EXTERNAL_LIBS_FIXUP ${MACOS_EXTERNAL_LIBS_FIXUP} CACHE INTERNAL "")
-