Set default MAKE=make on FreeBSD (#2263)

This was set to gmake in https://github.com/rbenv/ruby-build/pull/1381
as a workaround for https://bugs.ruby-lang.org/issues/16331



YJIT builds in Ruby 3.3 previews require the use of BSD make on these
platforms, and no supported version of MRI requires the use of gmake, so
revert this.

JRuby continues to require gmake for jruby-launcher.

Fixes #2262

Co-authored-by: Mislav Marohnić <git@mislav.net>