Error build if ICU or IConv support was requested but is not available.

[Flamefire]

This checks for the explicit commandline setting.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.88%. Comparing base (6b79d8b) to head (ee767a7).

❗ There is a different number of reports uploaded between BASE (6b79d8b) and HEAD (ee767a7). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (6b79d8b)	HEAD (ee767a7)
	3	2

Additional details and impacted files

@@             Coverage Diff              @@
##           develop     #247       +/-   ##
============================================
- Coverage    95.84%   78.88%   -16.97%     
============================================
  Files          117       94       -23     
  Lines        10410     7500     -2910     
============================================
- Hits          9977     5916     -4061     
- Misses         433     1584     +1151     

see 106 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6b79d8b...ee767a7. Read the comment docs.