9aa7c9a48 Export extern constants in embedder.h (flutter/engine#8550) (#30951)

https://github.com/flutter/engine/compare/f804c293f3ba...9aa7c9a48e93

git log f804c293f3baaec9ccec1e251293f6a3509223b8..9aa7c9a48e9342a450c3078e15c8d7923a338ede --no-merges --oneline
9aa7c9a48 Export extern constants in embedder.h (flutter/engine#8550)

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bin/internal/engine.version

-f804c293f3baaec9ccec1e251293f6a3509223b8
+9aa7c9a48e9342a450c3078e15c8d7923a338ede