d: Fix regressing test failures on ix86-solaris2.11

The _Unwind_Exception struct had its alignment adjusted to 16-bytes,
however malloc() on Solaris X86 is not guaranteed to allocate memory
aligned to 16-bytes as well.

	PR d/102837

libphobos/ChangeLog:

	* libdruntime/gcc/deh.d (ExceptionHeader.free): Use memset to reset
	contents of internal EH storage.

libphobos/libdruntime/gcc/deh.d

@@ -207,7 +207,7 @@ struct ExceptionHeader
      */
     static void free(ExceptionHeader* eh) @nogc
     {
-        *eh = ExceptionHeader.init;
+        __builtin_memset(eh, 0, ExceptionHeader.sizeof);
         if (eh != &ehstorage)
             __builtin_free(eh);
     }