feat: dynamic dependency debug info search

[pnwamk]

Now reopt and reopt-explore will attempt to find function types in the debug information of dynamic dependencies when analyzing a binary. If the dependency has previously been analyzed, the gleaned information will be cached in a REOPTHOME directory (getXdgDirectory XdgData ".reopt" by default or whatever path is specified by the REOPTHOMEenv var).

reopt

new reopt flags:

     --home                      Show location of the reopt home directory.
                                 Customizable via the REOPTHOME environment
                                 variable.
     --lib-dir=PATH              Additional location to search for dynamic
                                 dependencies.
     --debug-dir=PATH            Additional location to search for dynamic
                                 dependencies' debug info.

N.B., in addition to any specified --lib-dir directories, reopt will check the following default unix locations for libraries:

unixLibDirs = [ "/usr/local/lib"
              , "/usr/local/lib64"
              , "/usr/lib"
              , "/usr/lib64"
              , "/lib"
              , "/lib64"]

And in addition to any specified --debug-dir, reopt will query gdb to see where it looks for debug directories by executing the following:

gdb --batch --eval-command="show debug-file-directory"

reopt-explore

reopt-explore also now has the flags to add directories to the paths searched for libs and debug libs, i.e.:

     --lib-dir=PATH              Additional location to search for dynamic
                                 dependencies.
     --debug-dir=PATH            Additional location to search for dynamic
                                 dependencies' debug info.

and has a flag which switches the "exploration mode" to just looking for debug info (e.g., if there is a desire to pre-compute it on a machine before running reopt):

  -d --debug-info              Explore and export debug information for
                               functions only.

[pnwamk]

To do:

• Merge the associated https://github.com/GaloisInc/reopt-benchmark-binaries/tree/wip/dep-arg-analysis branch in reopt-benchmark-binaries, which adds compressed debug library info and a docker file where binaries, libs, and debug libs can be found

[pnwamk]

Comparing how the caching of dynamic dependencies' function type information affects run times seems to suggest it doesn't really make a difference so far... probably because of how little work we're doing in them (i.e., we just jump to their .debug_info section and scrape all the function type info).

Edit: the output differs greatly at present however, since on the first run any warnings/errors/etc encountered while parsing the lib do not appear at all on the second run.