ZS-86 issue in parsing dynsym section.

See merge request !12

The dynsym section is parsed by objdump/grep.  It's terrible and
needs to be implemented in C++ to reduce dependence on external tools
knowing what they are doing.

In this case, the terrible pattern matching with grep caused a symbol
defined in the binary to be missed, because `grep -v UND` was used
to determine whether a symbol "mattered".  1) symbol names might have
UND and get eliminated accidentally, but 2) (what really happened)
was that the symbol was defined in a section without a "link" field
in the dynsym section, thus objdump displayed the section name as UND
and thus the code skipped the symbol.  Don't use objdump to parse ELF
files!

Rida: Parsing of .plt.sec section added for x86/64 ubuntu 20 needed to be
updated to support x86/32 in ubuntu 20.

Fix-calls: Thunk checks aged poorly.  Revived/fixed some of them.

Shared libs need a reloc for a code pointer to live in rodata.
I found in ffmpeg that many spurious pins were occuring because constant
(particularly with relatively small values) data looked like code poitners
(because the code's load point is address 0 in a shared library).

To avoid these spuriosu pins, I extended the code pin algorithm
to check isDLL() (which includes shared objects) and for a reloc
before attempting to pin in the rodata.

A perf. optimization verifies that it _might_ result in a pin
before checking for a reloc, as checking for a reloc can be slow,
while checking for a possible pin location is fast.

Table size min was set to <=4 items, but readelf on ubuntu20
had a switch table with exactly 4 elements.  This caused
FII to miss the table size and subsequently include _many_ extra IBTs.
Ultimately, Zipr failed by trying to 68-sled an entire function due to
FII's failure.