[build] Don't use absolute 0 in dso_handle.ld

LLD is intentionally broken for handling SHN_ABS, STV_HIDDEN symbols.
So avoid using one in __dso_handle.ld.

Change-Id: I78d30ce511f229f46150012705f3af4864e527df

scripts/dso_handle.ld

@@ -9,5 +9,10 @@
  * no need for it, so just define the symbol away rather than wasting a
  * data word defining it as a real variable somewhere.  See
  * third_party/ulib/musl/src/exit/atexit.c for a more detailed explanation.
+ *
+ * LLD doesn't like it when this uses 0, because it makes that SHN_ABS and
+ * then is broken about handling STV_HIDDEN SHN_ABS symbols; it defines
+ * __ehdr_start as not SHN_ABS (though SHN_ABS is the only thing that
+ * actually makes sense for it), so that avoids the problem.
  */
-PROVIDE_HIDDEN(__dso_handle = 0);
+PROVIDE_HIDDEN(__dso_handle = __ehdr_start);