Fix uninitialized data members (coverity)

cint/cintex/src/ROOTClassEnhancer.cxx

core/meta/src/TDataType.cxx

hist/hist/src/TFormula.cxx

io/io/src/TKeyMapFile.cxx

io/io/src/TMapFile.cxx

io/sql/src/TSQLFile.cxx

io/xml/src/TXMLFile.cxx

io/xmlparser/src/TXMLParser.cxx

math/matrix/inc/TMatrixTUtils.h

math/matrix/src/TDecompSparse.cxx

math/matrix/src/TMatrixTUtils.cxx

misc/table/src/TDataSetIter.cxx

misc/table/src/TFileIter.cxx

tree/treeplayer/inc/TBranchProxyDirector.h