Fix off-by-one error when checking workspace_layout arguments

[oranenj]

If the configuration file contains:

workspace_layout auto left

or anything similar, the code checking the configuration will ignore the command and output an error.

The reason is easily confirmed with GDB:

(gdb) break cmd_workspace_layout
Breakpoint 1 at 0x16240: file /usr/src/debug/sway-master/sway/commands/workspace_layout.c, line 5.
(gdb) run
Starting program: /usr/bin/sway 
Missing separate debuginfos, use: dnf debuginfo-install glibc-2.24-4.fc25.x86_64
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Detaching after fork from child process 8799.
Detaching after fork from child process 8800.

Breakpoint 1, cmd_workspace_layout (argc=2, argv=0x559a6f093d98)
    at /usr/src/debug/sway-master/sway/commands/workspace_layout.c:5
5	struct cmd_results *cmd_workspace_layout(int argc, char **argv) {
(gdb) print argv[0]
$1 = 0x559a6f0942a0 "auto"
(gdb) print argv[1]
$2 = 0x559a6f093780 "left"

[ddevault]

Can you associate the email address you committed with to your GitHub account?

[oranenj]

Oh, I committed it with the wrong (work) identity. Let me fix that.

[ddevault]

Thanks!