[WebAssembly] fix bug in finding .tdata segment

[quantum]

Summary

Fix bug in wasm-ld's Writer::createInitTLSFunction that only finds .tdata if it's the first section.

[sbc100]

Maybe add a test for this?

[quantum]

Change test to put non-TLS variables first

lld/wasm/Writer.cpp

if (!WasmSym::initTLS->isLive())
     return;
 
   std::string bodyContent;
   {
     raw_string_ostream os(bodyContent);
 
     OutputSegment *tlsSeg = nullptr;
     for (auto *seg : segments) {
-      if (seg->name == ".tdata")
+      if (seg->name == ".tdata") {
         tlsSeg = seg;
         break;
       }
+    }
 
     writeUleb128(os, 0, "num locals");
     if (tlsSeg) {
       writeU8(os, WASM_OPCODE_LOCAL_GET, "local.get");
       writeUleb128(os, 0, "local index");
 
       writeU8(os, WASM_OPCODE_GLOBAL_SET, "global.set");
       writeUleb128(os, WasmSym::tlsBase->getGlobalIndex(), "global index");