issue #10017: TestGdbPython 'print mapvar' is reported to fail on ppc64.
issue #10002: TestGdbPython 'print mapvar' is reported to fail on arm hardfloat.

The testcase now uses plain line number in main.  Unwinding issues are
unrelated to the GDB map prettyprinter feature.

Remove arch-specific t.Skip()s from those two issues.

Fixes #10017
Fixes #10002

Change-Id: I9d50ffe2f3eb7bf65dd17c8c76a2677571de68ba
Reviewed-on: https://go-review.googlesource.com/6267Reviewed-by: Minux Ma <minux@golang.org>