support/gnuconfig/config.sub: add C-SKY support

Modify config.sub so that it knows about the C-SKY
architecture. Without this, all autotools projects fail to build on
C-SKY.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
[Thomas: improved commit log]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

support/gnuconfig/config.sub

@@ -254,6 +254,7 @@ case $basic_machine in
 	| arc | arceb \
 	| arm | arm[bl]e | arme[lb] | armv[2-8] | armv[3-8][lb] | armv7[arm] \
 	| avr | avr32 \
+	| csky \
 	| ba \
 	| be32 | be64 \
 	| bfin \
@@ -376,6 +377,7 @@ case $basic_machine in
 	| alphapca5[67]-* | alpha64pca5[67]-* | arc-* | arceb-* \
 	| arm-*  | armbe-* | armle-* | armeb-* | armv*-* \
 	| avr-* | avr32-* \
+	| csky-* \
 	| ba-* \
 	| be32-* | be64-* \
 	| bfin-* | bs2000-* \