hyperv: Build and install where supported

Remove the hard-coded dependency on HYPERV being only x86. Instead, 100%
rely on MK_HYPERV. It's always right (since it's marked BROKEN (so set
to "no") on architectures we don't support).

Sponsored by:		Netflix
Reviewed by:		bz
Differential Revision:	https://reviews.freebsd.org/D38306

libexec/Makefile

@@ -10,6 +10,7 @@ SUBDIR=	${_atf} \
 	${_dma} \
 	flua \
 	getty \
+	${_hyperv} \
 	${_mail.local} \
 	${_makewhatis.local} \
 	${_mknetid} \
@@ -64,6 +65,10 @@ _comsat=	comsat
 _dma=		dma
 .endif
 
+.if ${MK_HYPERV} != "no"
+_hyperv+=	hyperv
+.endif
+
 .if ${MK_NIS} != "no"
 _mknetid=	mknetid
 _ypxfr=		ypxfr

libexec/Makefile.amd64

@@ -1,5 +0,0 @@
-# $FreeBSD$
-
-.if ${MK_HYPERV} != "no"
-SUBDIR+=	hyperv
-.endif

libexec/Makefile.i386

@@ -1,5 +0,0 @@
-# $FreeBSD$
-
-.if ${MK_HYPERV} != "no"
-SUBDIR+=	hyperv
-.endif