Function definition by C include header list. Fixes #237

[Konstantin8105]

Close #237

---

This change is 

[codecov]

Codecov Report

Merging #627 into master will increase coverage by 0.2%.
The diff coverage is 96.03%.

@@            Coverage Diff            @@
##           master     #627     +/-   ##
=========================================
+ Coverage   80.28%   80.49%   +0.2%     
=========================================
  Files         158      158             
  Lines        8178     8202     +24     
=========================================
+ Hits         6566     6602     +36     
+ Misses       1241     1229     -12     
  Partials      371      371

Impacted Files	Coverage Δ
program/program.go	87.93% <100%> (+0.32%)	⬆️
main.go	55.88% <100%> (+0.65%)	⬆️
transpiler/call.go	69.46% <100%> (+1.32%)	⬆️
program/function_definition.go	100% <100%> (ø)	⬆️
transpiler/functions.go	90.35% <100%> (ø)	⬆️
preprocessor/preprocessor.go	82.12% <87.09%> (+6.38%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 05551f0...6f75731. Read the comment docs.

[elliotchance]

Reviewed 8 of 8 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

---

Comments from Reviewable

[elliotchance]

Review status: all files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

---

a discussion (no related file):
This is fine, I just can't merge until the conflicts are resolved.

---

Comments from Reviewable

[elliotchance]

Reviewed 2 of 2 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved.

---

Comments from Reviewable