Interface-independent wrapping

[mplegendre]

An initial implementation of interface-independent wrapping, for feedback purposes. Use the new gotcha_sigfree_wrap() to wrap with pre/post wrappers that are independent of a function's signature, as discussed in #55.

Before merging this needs debugging prints, more tests, ppc64 support, and documentation.

This will also be complimented with a new gotcha query interface for listing libraries/symbols, which will allow one to do operations like wrap all functions exported from an arbitrary library.

[codecov-io]

Codecov Report

Merging #77 into develop will increase coverage by 0.67%.
The diff coverage is 91%.

@@            Coverage Diff             @@
##           develop     #77      +/-   ##
==========================================
+ Coverage    82.42%   83.1%   +0.67%     
==========================================
  Files           10      11       +1     
  Lines         1064    1160      +96     
==========================================
+ Hits           877     964      +87     
- Misses         187     196       +9

Impacted Files	Coverage Δ
src/tool.c	58.33% <100%> (+0.78%)	⬆️
src/gotcha.c	90.49% <100%> (+0.54%)	⬆️
src/thin.c	89.02% <89.02%> (ø)

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[mplegendre]

Added ppc64le support and tests, but still need documentation on new interfaces

[mplegendre]

This should be ready for review

[DavidPoliakoff]

Cool. It'll probably be a couple of weeks before I can really give it a look, but thanks for putting it together

[DavidPoliakoff]

@mplegendre , last I looked I thought I had approved this? Oops. I'll approve it in a review now