Enable --gc-sections for WebAssembly targets

This effectively reverts 3a366cc.
After swiftlang/swift#71768, we don't have any
reason to disable `--gc-sections` for WebAssembly targets.
Note that the new wasm segment flags are only supported by the latest
LLVM and wasm-ld, but we can assume that toolchains or Swift SDKs for
WebAssembly have wasm-ld built from the latest LLVM.

Author: kateinoigakukun

Sources/Build/BuildDescription/ProductBuildDescription.swift

@@ -119,15 +119,6 @@ public final class ProductBuildDescription: SPMBuildCore.ProductBuildDescription
                 return ["-Xlinker", "-dead_strip"]
             } else if triple.isWindows() {
                 return ["-Xlinker", "/OPT:REF"]
-            } else if triple.arch == .wasm32 {
-                // FIXME: wasm-ld strips data segments referenced through __start/__stop symbols
-                // during GC, and it removes Swift metadata sections like swift5_protocols
-                // We should add support of SHF_GNU_RETAIN-like flag for __attribute__((retain))
-                // to LLVM and wasm-ld
-                // This workaround is required for not only WASI but also all WebAssembly triples
-                // using wasm-ld (e.g. wasm32-unknown-unknown). So this branch is conditioned by
-                // arch == .wasm32
-                return []
             } else {
                 return ["-Xlinker", "--gc-sections"]
             }