testsuite: fix T16180 on wasm

This commit fixes T16180 on wasm once TH support is flipped on. The
fix is simply adding right asm code for wasm.

(cherry picked from commit 69bb4745)

testsuite/tests/th/T16180.hs

@@ -11,7 +11,14 @@ $(do
    -- could reuse FP_LEADING_UNDERSCORE from aclocal.m4 for this
    -- somehow, but this hopefully is OK for now.
    addForeignSource LangAsm $ unlines
-#if defined(darwin_HOST_OS) || (defined(mingw32_HOST_OS) && WORD_SIZE_IN_BITS == 32)
+#if defined(wasm32_HOST_ARCH)
+      [ ".section .rodata.mydata,\"\",@"
+      , ".globl mydata"
+      , "mydata:"
+      , ".asciz \"Hello world\""
+      , ".size mydata, 12"
+      ]
+#elif defined(darwin_HOST_OS) || (defined(mingw32_HOST_OS) && WORD_SIZE_IN_BITS == 32)
       [ ".global \"_mydata\""
       , "_mydata:"
       , ".ascii \"Hello world\\0\""