CMake: Qt Creator Static build support

This adds the build system feature that allows Qt Creator's libraries
and plugins to be compiled statically.

Fixes some symbol clashes when all plugins are linked into the same
executable.

Support for actually loading static plugins will be added in a separate
commit.

The feature is controlled by QTC_STATIC_BUILD which by default is OFF.

Change-Id: I1fab7953c43e42dc75619e35660029ee067106df
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

cmake/Findyaml-cpp.cmake

@@ -22,9 +22,7 @@ else()
   endif()
   set(YAML_SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/../src/libs/3rdparty/yaml-cpp)
   add_qtc_library(yaml-cpp
-    DEFINES YAML_CPP_DLL yaml_cpp_EXPORTS
     INCLUDES ${YAML_SOURCE_DIR}/include
-    PUBLIC_DEFINES YAML_CPP_DLL
     PUBLIC_INCLUDES ${YAML_SOURCE_DIR}/include
     PROPERTIES AUTOMOC OFF AUTOUIC OFF
     SOURCES
@@ -116,6 +114,12 @@ else()
       ${YAML_SOURCE_DIR}/src/tag.h
       ${YAML_SOURCE_DIR}/src/token.h
     )
+    if (NOT QTC_STATIC_BUILD)
+      extend_qtc_target(yaml-cpp
+        DEFINES yaml_cpp_EXPORTS
+        PUBLIC_DEFINES YAML_CPP_DLL)
+    endif()
+
     if(TARGET yaml-cpp)
       set(yaml-cpp_FOUND 1)
       set_package_properties(yaml-cpp PROPERTIES DESCRIPTION "using internal src/libs/3rdparty/yaml-cpp")