Suppress spurious warning about RCTCxxModule (#19880)
Suppress spurious warning about RCTCxxModule (#19880)

Summary:
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On a relatively stock / default setup of RN on iOS you'll see the warning "Class RCTCxxModule was not exported. Did you forget to use RCT_EXPORT_MODULE()?" pop up on every launch. This change resolves that issue.

Fixes #14806 .

This supersedes PR #19794 .

Try a fresh project by following the RN iOS tutorial, and observe that there are no more warnings after making this change.

[IOS] [MINOR] [CxxBridge] - Fix "Class RCTCxxModule was not exported"
Closes https://github.com/facebook/react-native/pull/19880

Differential Revision: D8653809

Pulled By: hramos

fbshipit-source-id: c48529c2d74ddd40a90bc0e06e405078e25b72e3

pandiaraj44/react-native,janicduplessis/react-native,myntra/react-native,javache/react-native,facebook/react-native,pandiaraj44/react-native,myntra/react-native,facebook/react-native,pandiaraj44/react-native,janicduplessis/react-native,pandiaraj44/react-native,exponentjs/react-native,exponent/react-native,myntra/react-native,javache/react-native,exponentjs/react-native,javache/react-native,javache/react-native,exponent/react-native,hoangpham95/react-native,facebook/react-native,hammerandchisel/react-native,facebook/react-native,facebook/react-native,javache/react-native,arthuralee/react-native,hammerandchisel/react-native,javache/react-native,arthuralee/react-native,hoangpham95/react-native,javache/react-native,pandiaraj44/react-native,janicduplessis/react-native,arthuralee/react-native,facebook/react-native,exponentjs/react-native,hoangpham95/react-native,hammerandchisel/react-native,hammerandchisel/react-native,pandiaraj44/react-native,myntra/react-native,exponentjs/react-native,hoangpham95/react-native,exponentjs/react-native,hoangpham95/react-native,myntra/react-native,pandiaraj44/react-native,exponent/react-native,janicduplessis/react-native,arthuralee/react-native,hoangpham95/react-native,janicduplessis/react-native,janicduplessis/react-native,myntra/react-native,exponent/react-native,exponent/react-native,hoangpham95/react-native,hammerandchisel/react-native,myntra/react-native,exponent/react-native,hammerandchisel/react-native,pandiaraj44/react-native,hammerandchisel/react-native,arthuralee/react-native,facebook/react-native,javache/react-native,facebook/react-native,facebook/react-native,myntra/react-native,janicduplessis/react-native,exponent/react-native,exponent/react-native,exponentjs/react-native,exponentjs/react-native,hammerandchisel/react-native,javache/react-native,janicduplessis/react-native,myntra/react-native,exponentjs/react-native,hoangpham95/react-native