This was causing excessive 'uname -s' executions during Poudriere dependency
calculations.  The reasoning is due to HAVE_COMPAT_IA32_KERN having a newline
quoted at the end of it as '\ ' by bmake:

  # make -f Mk/bsd.port.mk -V 'HAVE_COMPAT_IA32_KERN=${HAVE_COMPAT_IA32_KERN:Q}' | cat -v
  HAVE_COMPAT_IA32_KERN=YES\

This resulted in the following being executed:

  export HAVE_COMPAT_IA32_KERN="YES OPSYS=FreeBSD"

With hat:	portmgr