compiler: remove escapes_ field from Variable and Result_variable

The fields were set to true initially and never set to false.
These were left over from an earlier attempt at escape analysis.

Change-Id: I1b8e8a1a27594df6c6fc7465d5244cdc676d2a0a
Reviewed-on: https://go-review.googlesource.com/c/155750
Reviewed-by: Cherry Zhang <cherryyz@google.com>
3 files changed