condformats_serialization_generate.py: support for aarch64

LLVM/Clang on AArch64 will report that most AST nodes are not
definition, which is not true. The following modifies script to
check definition based on location information directly (file, line,
 and column).

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Convert missed two is_definition() calls to is_definition_by_loc()

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #3978 from davidlt/cond-boost-aarch64-71x

CondFormats/Serialization -- Cond boost aarch64 71x