STYLE: more uniform file endings (C -> cxx)

src/adiosFoam/Make/files

src/adiosFoam/adiosFoam.H

src/adiosFoam/adiosFoam.cxx

src/adiosFoam/controls/adiosRegionControl.H

src/adiosFoam/controls/adiosRegionControl.cxx

src/adiosFoam/core/adiosCore.H

src/adiosFoam/core/adiosCore.cxx

src/adiosFoam/read/adiosReader.H

src/adiosFoam/read/adiosReader.cxx

src/adiosFoam/read/adiosReader.txx

src/adiosFoam/read/adiosReaderCloud.cxx

src/adiosFoam/read/adiosReaderField.cxx

src/adiosFoam/time/adiosTime.H

src/adiosFoam/time/adiosTime.cxx

src/adiosFoam/write/adiosCoreWrite.H

src/adiosFoam/write/adiosCoreWrite.cxx

src/adiosFoam/write/adiosCoreWrite.txx

src/adiosFoam/write/adiosCoreWriteAttr.cxx

src/adiosFoam/write/adiosCoreWriteCloud.cxx

src/adiosFoam/write/adiosCoreWriteField.cxx