Revert "cmake build: Disable clangpchmanagerbackend and refactoringbackend"

The change breaks the dev package:

The imported target "QtCreator::clangrefactoringbackend_lib" references
the file
"/home/qt/work/build/qtc_build/lib/qtcreator/libclangrefactoringbackend_lib.a"
but this file does not exist.

This reverts commit 20a6207459.

Change-Id: I68f3b6948bde611b9e5b841d1fde2b136877cbfc
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

cmake/QtCreatorAPI.cmake

@@ -541,7 +541,7 @@ endfunction()
 
 function(add_qtc_executable name)
   cmake_parse_arguments(_arg "SKIP_INSTALL;SKIP_TRANSLATION;ALLOW_ASCII_CASTS"
-    "DESTINATION;COMPONENT;BUILD_DEFAULT"
+    "DESTINATION;COMPONENT"
     "DEPENDS;DEFINES;INCLUDES;SOURCES;EXPLICIT_MOC;SKIP_AUTOMOC;EXTRA_TRANSLATIONS;PROPERTIES" ${ARGN})
 
   if ($_arg_UNPARSED_ARGUMENTS)
@@ -556,11 +556,7 @@ function(add_qtc_executable name)
   update_cached_list(__QTC_EXECUTABLES "${name}")
 
   string(TOUPPER "BUILD_EXECUTABLE_${name}" _build_executable_var)
-  if (DEFINED _arg_BUILD_DEFAULT)
-    set(_build_executable_default ${_arg_BUILD_DEFAULT})
-  else()
   set(_build_executable_default ${BUILD_EXECUTABLES_BY_DEFAULT})
-  endif()
   if (DEFINED ENV{QTC_${_build_executable_var}})
     set(_build_executable_default "$ENV{QTC_${_build_executable_var}}")
   endif()

src/plugins/clangpchmanager/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_qtc_plugin(ClangPchManager
-  CONDITION TARGET libclang AND TARGET clangpchmanagerbackend
+  BUILD_DEFAULT OFF
+  CONDITION TARGET libclang
   DEPENDS ClangSupport CPlusPlus
   DEFINES CLANGPCHMANAGER_LIB
   PLUGIN_DEPENDS Core CppTools

src/plugins/clangrefactoring/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_qtc_plugin(ClangRefactoring
-  CONDITION TARGET libclang AND TARGET clangrefactoringbackend
+  BUILD_DEFAULT OFF
+  CONDITION TARGET libclang
   DEPENDS ClangSupport CPlusPlus
   PLUGIN_DEPENDS Core CppTools TextEditor ClangPchManager
   SOURCES ${TEST_SOURCES}

src/tools/clangpchmanagerbackend/CMakeLists.txt

@@ -1,7 +1,6 @@
 add_subdirectory(source)
 
 add_qtc_executable(clangpchmanagerbackend
-  BUILD_DEFAULT OFF
   DEPENDS
     clangrefactoringbackend_lib clangpchmanagerbackend_lib
     Sqlite ClangSupport

src/tools/clangrefactoringbackend/CMakeLists.txt

@@ -1,7 +1,6 @@
 add_subdirectory(source)
 
 add_qtc_executable(clangrefactoringbackend
-  BUILD_DEFAULT OFF
   DEPENDS
     clangrefactoringbackend_lib Sqlite ClangSupport
   SOURCES