Added support for SCO UnixWare 7.

build/autoconf/config.guess

@@ -638,6 +638,11 @@ EOF
         # Use sysv4.2uw... so that sysv4* matches it.
 	echo ${UNAME_MACHINE}-pc-sysv4.2uw${UNAME_VERSION}
 	exit 0 ;;
+    i?86:UnixWare:*:*)
+        # Unixware 7 is the first attempt at a useful OS description.
+        # Use sysv4.2uw... so that sysv4* matches it.
+	echo ${UNAME_MACHINE}-pc-sysv4.2uw${UNAME_VERSION}
+	exit 0 ;;
     i?86:*:4.*:* | i?86:SYSTEM_V:4.*:*)
 	if grep Novell /usr/include/link.h >/dev/null 2>/dev/null; then
 		echo ${UNAME_MACHINE}-univel-sysv${UNAME_RELEASE}