config.sub: Treat i386-pc-rtmk-nova as a 4-part system name.

Handle ‘i386-nova’ as shorthand for a 4-part system name,
kernel=rtmk os=nova, instead of a canonicalized OS name with
a dash in the middle, os=rtmk-nova.

RTMK <https://rtmk.sourceforge.net/> is a microkernel.
Nova <https://www.nongnu.org/nova> is an OS written on top of that
microkernel.  The short system name ‘i386-nova’ was therefore defined
to canonicalize to ‘i386-pc-rtmk-nova’, I think prior to the general
introduction of 4-part system names.  ‘i386-pc-rtmk-nova’ still makes
sense under the rules for interpreting 4-part names, but nowadays the
logic for validating canonicalized name components rejects OS names
with a dash in the middle.  Feeding kernel=rtmk os=nova to that logic,
instead, does the Right Thing.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>

config.sub

@@ -1633,7 +1633,8 @@ case $os in
 		os=sysv
 		;;
 	nova*)
-		os=rtmk-nova
+		kernel=rtmk
+		os=nova
 		;;
 	# Preserve the version number of sinix5.
 	sinix5.*)
@@ -2017,6 +2018,7 @@ case $os in
 	| nextstep* \
 	| nindy* \
 	| nonstopux* \
+	| nova* \
 	| nsk* \
 	| nucleus* \
 	| nx6 \
@@ -2197,6 +2199,8 @@ case $kernel-$os-$obj in
 		;;
 	os2-emx-)
 		;;
+	rtmk-nova-)
+		;;
 	*-eabi*- | *-gnueabi*-)
 		;;
 	none--*)

testsuite/config-sub.data

@@ -332,6 +332,7 @@ i386-mingw32					i386-pc-mingw32
 i386-msys					i386-pc-msys
 i386-netbsd					i386-pc-netbsd
 i386-next-openstep4				i386-next-openstep4
+i386-nova					i386-pc-rtmk-nova
 i386-openbsd					i386-pc-openbsd
 i386-os2					i386-pc-os2
 i386-pc-nacl					i386-pc-nacl