perlasm/sparcv9_modes.pl: make it work even with seasoned perl.

PR: 3130

crypto/perlasm/sparcv9_modes.pl

@@ -1657,8 +1657,8 @@ sub emit_assembler {
 	s/\b(camellia_[^s]+)\s+(%f[0-9]{1,2}),\s*(%f[0-9]{1,2}),\s*(%f[0-9]{1,2})/
 		&uncamellia3($1,$2,$3,$4)
 	 /geo or
-	s/\b(des_\w+)\s+(?<rs1>%f[0-9]{1,2}),\s*(?<rs2>[%fx0-9]+)(,\s*(?<rs3>%f[0-9]{1,2})(,\s*(?<rs4>%f[0-9]{1,2}))?)?/
-		&undes($1,$+{rs1},$+{rs2},$+{rs3},$+{rs4})
+	s/\b(des_\w+)\s+(%f[0-9]{1,2}),\s*([%fx0-9]+)(?:,\s*(%f[0-9]{1,2})(?:,\s*(%f[0-9]{1,2}))?)?/
+		&undes($1,$2,$3,$4,$5)
 	 /geo or
 	s/\b(mov[ds]to\w+)\s+(%f[0-9]{1,2}),\s*(%[goli][0-7])/
 		&unmovxtox($1,$2,$3)