vndk-def: Revise vdex file parser

This commit updates vdex file parser so that it can parse vdex file v19.

Test: vndk_definition_tool.py check-dep \
  --check-apk \
  --system ${ANDROID_PRODUCT_OUT}/system \
  --vendor ${ANDROID_PRODUCT_OUT}/vendor \
  --tag-file dataset/eligible-list-${VER}.csv

Change-Id: I8161eab1936ab3f06c3295cf98d8ad09901ce8d3