[binutils-gdb] Define HAVE_NATIVE_GCORE_HOST on NetBSD

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT 28ad437d7af2fe5bf83dafb4e733978d0b142edb ***

Author: Kamil Rytarowski <n54@gmx.com>
Branch: master
Commit: 28ad437d7af2fe5bf83dafb4e733978d0b142edb

Define HAVE_NATIVE_GCORE_HOST on NetBSD

NetBSD ships with gcore(1) againg since the version 2.0.
This tool is functional and actively maintained.

gdb/ChangeLog
2017-09-06  Kamil Rytarowski  <n54@gmx.com>

	* configure.nat: Define HAVE_NATIVE_GCORE_HOST on NetBSD.