Reimplement patch to disable Asyncronous IO in virtualbox-ose 6 as

an option, leaving AIO enabled by default, so no functional change
in default build.

Requested/Suggested by:	David G Lawrence <dg@dglawrence.com>

emulators/virtualbox-ose/Makefile

@@ -53,11 +53,12 @@ VBOX_PROGS=	VBoxAutostart VBoxBalloonCtrl VBoxBugReport VBoxHeadless \
 VBOX_UTILS=	VBoxExtPackHelperApp VBoxNetAdpCtl VBoxNetDHCP VBoxNetNAT \
 		VBoxSVC VBoxXPCOMIPCD
 
-OPTIONS_DEFINE=	ALSA DBUS DEBUG GUESTADDITIONS MANUAL NLS OPUS PULSEAUDIO \
+OPTIONS_DEFINE=	AIO ALSA DBUS DEBUG GUESTADDITIONS MANUAL NLS OPUS PULSEAUDIO \
 		PYTHON QT5 R0LOGGING UDPTUNNEL VDE VNC WEBSERVICE VPX X11
-OPTIONS_DEFAULT=	DBUS QT5 UDPTUNNEL VNC WEBSERVICE X11
+OPTIONS_DEFAULT=	AIO DBUS QT5 UDPTUNNEL VNC WEBSERVICE X11
 OPTIONS_SUB=	yes
 
+AIO_DESC=	Enable Asyncronous IO support (check pkg-message)
 DEBUG_DESC=	Debug symbols, additional logs and assertions
 GUESTADDITIONS_DESC=	Build with Guest Additions
 MANUAL_DESC=	Build with user manual
@@ -323,6 +324,10 @@ post-patch:
 	    -e 's|^versions =.*|versions = ["${PYTHON_VER}${PYTHON_ABIVER}"]|' \
 	    ${WRKSRC}/src/libs/xpcom18a4/python/gen_python_deps.py
 
+post-patch-AIO-off:
+	@${REINPLACE_CMD} 's|r3/freebsd/fileaio-freebsd.cpp|r3/posix/fileaio-posix.cpp|' \
+		${WRKSRC}/src/VBox/Runtime/Makefile.kmk
+
 do-build:
 	cd ${WRKSRC} && ${SH} -c '. ${WRKSRC}/env.sh && \
 	    ${KMK_CONFIG} ${LOCALBASE}/bin/kmk ${KMK_FLAGS}'