Use more target-centric cmake code

kmail/editorconvertertextplugins/markdown/markdownlib/CMakeLists.txt

-set(kmailmarkdownlib_SRCS
+add_library(kmailmarkdown)
+
+target_sources(kmailmarkdown PRIVATE
     markdownpreviewwidget.cpp
     markdownconfigurewidget.cpp
     markdownconfiguredialog.cpp
@@ -15,7 +17,6 @@ set(kmailmarkdownlib_SRCS
 
 
 
-add_library(kmailmarkdown ${kmailmarkdownlib_SRCS})
 if (COMPILE_WITH_UNITY_CMAKE_SUPPORT)
     set_target_properties(kmailmarkdown PROPERTIES UNITY_BUILD ON)
 endif()

kmail/grammarplugins/grammarcommon/CMakeLists.txt

-set(grammarcommon_SRCS
+add_library(grammarcommon)
+
+target_sources(grammarcommon PRIVATE
     grammarerror.cpp
     grammarresulttextedit.cpp
     grammarresultwidget.cpp
     )
 
-ecm_qt_declare_logging_category(grammarcommon_SRCS HEADER grammarcommon_debug.h IDENTIFIER LIBGRAMMARCOMMON_LOG CATEGORY_NAME org.kde.pim.libgrammarcommon
+ecm_qt_declare_logging_category(grammarcommon HEADER grammarcommon_debug.h IDENTIFIER LIBGRAMMARCOMMON_LOG CATEGORY_NAME org.kde.pim.libgrammarcommon
     DESCRIPTION "kdepim-addons (libgramalecte common)"
     EXPORT KDEPIMADDONS
     )
 
 
-
-add_library(grammarcommon ${grammarcommon_SRCS})
 generate_export_header(grammarcommon BASE_NAME grammarcommon)
 if (COMPILE_WITH_UNITY_CMAKE_SUPPORT)
     set_target_properties(grammarcommon PROPERTIES UNITY_BUILD ON)

kmail/grammarplugins/languagetool/src/CMakeLists.txt

-set(kmaillanguagetool_SRCS
+add_library(kmaillanguagetool)
+target_sources(kmaillanguagetool PRIVATE
     languagetoolparser.cpp
     languagetoolgrammarerror.cpp
     languagetoolresultwidget.cpp
@@ -13,13 +14,13 @@ set(kmaillanguagetool_SRCS
     languagetoolupdatecombobox.cpp
     )
 
-ecm_qt_declare_logging_category(kmaillanguagetool_SRCS HEADER liblanguagetool_debug.h IDENTIFIER LIBLANGUAGE_PLUGIN_LOG CATEGORY_NAME org.kde.pim.liblanguagetoolplugin
+ecm_qt_declare_logging_category(kmaillanguagetool HEADER liblanguagetool_debug.h IDENTIFIER LIBLANGUAGE_PLUGIN_LOG CATEGORY_NAME org.kde.pim.liblanguagetoolplugin
     DESCRIPTION "kdepim-addons (liblanguagetool)"
     EXPORT KDEPIMADDONS
     )
 
 
-add_library(kmaillanguagetool ${kmaillanguagetool_SRCS})
+
 if (COMPILE_WITH_UNITY_CMAKE_SUPPORT)
     set_target_properties(kmaillanguagetool PROPERTIES UNITY_BUILD ON)
 endif()