Doc: Use explicit linkage with target_link_libraries

The Professional CMake book suggests always using explicit linkage with
target_link_libraries, so let's use that.

Whether to use PUBLIC or PRIVATE depends on the context. But let's
be conservative and advise on using PRIVATE by default.

Task-number: QTBUG-88935
Change-Id: I12b80ee85be9f6916f1e4dea6b1c9cb29e03c20f
Reviewed-by: Craig Scott <craig.scott@qt.io>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
(cherry picked from commit 130b2090147e0d28e35fd736fbefcd588c0014f6)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/concurrent/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS Concurrent REQUIRED)
-target_link_libraries(mytarget Qt6::Concurrent)
+target_link_libraries(mytarget PRIVATE Qt6::Concurrent)
 #! [cmake_use]

src/corelib/doc/snippets/overview/using-qt-core.cmake

@@ -1,2 +1,2 @@
 find_package(Qt6 COMPONENTS Core REQUIRED)
-target_link_libraries(mytarget Qt6::Core)
+target_link_libraries(mytarget PRIVATE Qt6::Core)

src/dbus/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS DBus REQUIRED)
-target_link_libraries(mytarget Qt6::DBus)
+target_link_libraries(mytarget PRIVATE Qt6::DBus)
 #! [cmake_use]

src/gui/doc/snippets/overview/using-qt-gui.cmake

@@ -1,2 +1,2 @@
 find_package(Qt6 COMPONENTS Gui REQUIRED)
-target_link_libraries(mytarget Qt6::Gui)
+target_link_libraries(mytarget PRIVATE Qt6::Gui)

src/network/doc/snippets/CMakeLists.txt

@@ -8,5 +8,5 @@ add_executable(mytarget
 
 # ![0]
 find_package(Qt6 COMPONENTS Network REQUIRED)
-target_link_libraries(mytarget Qt6::Network)
+target_link_libraries(mytarget PRIVATE Qt6::Network)
 # ![0]

src/opengl/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS OpenGL REQUIRED)
-target_link_libraries(mytarget Qt6::OpenGL)
+target_link_libraries(mytarget PRIVATE Qt6::OpenGL)
 #! [cmake_use]

src/printsupport/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS PrintSupport REQUIRED)
-target_link_libraries(mytarget Qt6::PrintSupport)
+target_link_libraries(mytarget PRIVATE Qt6::PrintSupport)
 #! [cmake_use]

src/sql/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS Sql REQUIRED)
-target_link_libraries(mytarget Qt6::Sql)
+target_link_libraries(mytarget PRIVATE Qt6::Sql)
 #! [cmake_use]

src/testlib/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS Test REQUIRED)
-target_link_libraries(mytarget Qt6::Test)
+target_link_libraries(mytarget PRIVATE Qt6::Test)
 #! [cmake_use]

src/widgets/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS Widgets REQUIRED)
-target_link_libraries(mytarget Qt6::Widgets)
+target_link_libraries(mytarget PRIVATE Qt6::Widgets)
 #! [cmake_use]

src/xml/doc/snippets/CMakeLists.txt

@@ -1,4 +1,4 @@
 #! [cmake_use]
 find_package(Qt6 COMPONENTS Xml REQUIRED)
-target_link_libraries(mytarget Qt6::Xml)
+target_link_libraries(mytarget PRIVATE Qt6::Xml)
 #! [cmake_use]