clang-tidy: Use default member initialization

.clang-tidy

Source/CTest/cmCTestBuildHandler.cxx

Source/CTest/cmCTestGIT.cxx

Source/cmCPluginAPI.cxx

Source/cmCTest.h

Source/cmCacheManager.h

Source/cmCommand.h

Source/cmComputeLinkDepends.h

Source/cmComputeLinkInformation.h

Source/cmCustomCommand.cxx

Source/cmDefinitions.h

Source/cmDepends.cxx

Source/cmDepends.h

Source/cmDependsC.cxx

Source/cmDependsC.h

Source/cmDependsFortran.cxx

Source/cmDependsFortran.h

Source/cmDocumentation.h

Source/cmDocumentationFormatter.cxx

Source/cmDocumentationFormatter.h