Add drmemtrace -record_syscall targets to function list file

We added a -record_syscall feature to drmemtrace but which syscalls are traced is not recorded anywhere today. It is useful to know up front which syscalls were traced; knowing their arg counts ahead of time also helps in parsing records. The proposal is to add the syscall entries to the funclist.log file.

When processing a trace on another machine it is not always simple to match up syscall numbers, but it's not clear how to solve that here unless the tracer can synthesize a string name for the syscall.

Start with drmemtrace's -record_syscall handling and the generation of funclist.log. Determine how traced syscall entries and argument counts can be recorded, then clarify how syscall names or numbers should be represented when processing a trace on another machine. Done means funclist.log identifies the syscalls captured by the trace and provides their argument counts.

Written by the indexing model from the issue text.