wasm: fix dyld for shared libraries created by llvm 20.x

This patch fixes wasm dyld script for shared libraries created by llvm
20.x. The __wasm_apply_data_relocs function is now optional and may be
omitted for shared libraries without any runtime relocatable data
segments, so only call __wasm_apply_data_relocs when it's present.

(cherry picked from commit cb60da24)
(cherry picked from commit 6bd4fd72)