PR 4311 - Function boundary tracing without debuginfo: Phase I

PR 4311 - Function boundary tracing without debuginfo: Phase I
* tapsets.cxx: Major rework of dwflpp, dwarf_query, and related
code to make do with elf info if dwarf info is absent, or
(in the case of vmlinux) make do with a System.map-style
symbol table if even the elf file is absent.
* main.cxx: Use getopt_long instead of getopt.	Added --kelf,
--kmap, --ignore-vmlinux, and --ignore-dwarf.
* hash.cxx, session.h, stap.1.in: Added --kelf, --kmap,
--ignore-vmlinux, and --ignore-dwarf.