The absence of symbol sizes broke build comparison that looks for and
ignores snapshots. Add symbol types for good measure to match the compiler
behavior.
Consider unknown operating systems to use as(1)-style assembly, which is
generally true. If an unknown operating system uses another syntax, the
generated files will fail to assemble and the porter should soon find
this script and add support for their operating system.
R=whesse@google.com
Review-Url: https://codereview.chromium.org/2939013002 .