BaseTools:Updata the output encoding of the Popen function

BaseTools:Updata the output encoding of the Popen function

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=2015

Not all output works in utf-8, so change the encoding to
the default

This patch is going to fix that issue.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>