runtime: handle DW_EH_PE_absptr in type table encoding

The type table encoding can be DW_EH_PE_absptr, but this case
was missing, which was causing abort on ARM32 EABI. Add the
missing case.

Change-Id: Id68d907b2fb0bc1868cb2c28a4cde867e3971736
Reviewed-on: https://go-review.googlesource.com/c/153857
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/libgo/runtime/go-unwind.c b/libgo/runtime/go-unwind.c
index c44755f..f4bbfb6 100644
--- a/libgo/runtime/go-unwind.c
+++ b/libgo/runtime/go-unwind.c
@@ -318,6 +318,8 @@
       case DW_EH_PE_sdata8:
       case DW_EH_PE_udata8:
         return 8;
+      case DW_EH_PE_absptr:
+        return sizeof(uintptr);
       default:
         break;
     }