Fix build issues in MSYS2

[pffang]

Fix build issues in MSYS2, and add an MSYS2 action to check build issues.

[minminlittleshrimp]

Hi @pffang
thanks for the patch.
Any test logs/provable proof run from you can be provided here?
How you make sure the patch run? what the patch fixed?
Can you provide detail analysis here?
Thanks

[pffang]

Hi @pffang thanks for the patch. Any test logs/provable proof run from you can be provided here? How you make sure the patch run? what the patch fixed? Can you provide detail analysis here? Thanks

I usually need to build dlt console tools in MSYS2 and use them on Windows.
At least dlt-convert can covert *.dlt files to text files on Windows.

And I also tried dlt-daemon and dlt-test-stress-client

$ build/src/daemon/dlt-daemon.exe
[1451895.771945]~DLT~ 1288~NOTICE   ~Starting DLT Daemon; DLT Package Version: 2.18.10 STABLE, Package Revision: , build on Feb  3 2026 09:58:34
-SYSTEMD -SYSTEMD_WATCHDOG -TEST -SHM

[1451895.777875]~DLT~ 1288~WARNING  ~Unable to set send timeout Socket operation on non-socket.
[1451895.778085]~DLT~ 1288~INFO     ~Activate connection type: 5
[1451895.779390]~DLT~ 1288~INFO     ~dlt_daemon_socket_open: Socket created
[1451895.780172]~DLT~ 1288~INFO     ~dlt_daemon_socket_open: Listening on ip 0.0.0.0 and port: 3490
[1451895.780444]~DLT~ 1288~INFO     ~dlt_daemon_socket_open: Socket send queue size: 64512
[1451895.780743]~DLT~ 1288~INFO     ~Activate connection type: 1
[1451895.781317]~DLT~ 1288~WARNING  ~dlt_daemon_unix_socket_open: unlink() failed: No such file or directory
[1451895.782741]~DLT~ 1288~INFO     ~Activate connection type: 9
[1451895.783244]~DLT~ 1288~INFO     ~Cannot open configuration file: /tmp/dlt-runtime.cfg
[1451895.783448]~DLT~ 1288~INFO     ~Ringbuffer configuration: 500000/10000000/500000
[1451895.783838]~DLT~ 1288~NOTICE   ~Failed to open ECU Software version file.
[1451895.784096]~DLT~ 1288~INFO     ~Switched to buffer state for socket connections.
[1451895.784515]~DLT~ 1288~WARNING  ~dlt_daemon_applications_load: cannot open file /tmp/dlt-runtime-application.cfg: No such file or directory
[1451900.470962]~DLT~ 1288~INFO     ~Activate connection type: 2
[1451900.471660]~DLT~ 1288~INFO     ~Switched to send buffer state for socket connections.
[1451900.472045]~DLT~ 1288~INFO     ~Switched to send direct state.
[1451915.021379]~DLT~ 1288~INFO     ~Deactivate connection type: 2
[1451915.021998]~DLT~ 1288~INFO     ~Switched to buffer state for socket connections.
[1451917.547640]~DLT~ 1288~NOTICE   ~Exiting DLT daemon due to signal: Interrupt
[1451917.549662]~DLT~ 1288~NOTICE   ~Exiting DLT daemon... [2]
[1451917.552447]~DLT~ 1288~NOTICE   ~Leaving DLT daemon

$ build/src/tests/dlt-test-stress-client.exe -a -v localhost
[1451900.455262]~DLT~ 1289~INFO     ~dlt_client_init: Init dlt client struct with default port: 3490.
[1451900.457390]~DLT~ 1289~INFO     ~dlt_file_init()
[1451900.459150]~DLT~ 1289~INFO     ~dlt_message_init()
[1451900.460663]~DLT~ 1289~INFO     ~dlt_filter_init()
[1451900.471098]~DLT~ 1289~INFO     ~dlt_client_connect: Connected to DLT daemon (localhost)
[1451900.472889]~DLT~ 1289~INFO     ~dlt_message_init()
[1451900.474305]~DLT~ 1289~INFO     ~dlt_message_read()
[1451900.476042]~DLT~ 1289~INFO     ~dlt_message_get_extraparameters()
[1451900.477374]~DLT~ 1289~INFO     ~dlt_message_read()
[1451900.478755]~DLT~ 1289~INFO     ~dlt_message_get_extraparameters()
[1451900.480031]~DLT~ 1289~INFO     ~dlt_message_read()
[1451900.481294]~DLT~ 1289~INFO     ~dlt_message_get_extraparameters()
[1451900.482628]~DLT~ 1289~INFO     ~dlt_message_read()

You can also check the change code. I didn't modify any logic, just fixed some compiling errors in MSYS2, and add a new GitHub action to check the building in MSYS2.

Most compiling errors are char-subscripts and unused errors. The POSIX C functions isdigit/ispunct/isspace accept int input value not char, please check https://pubs.opengroup.org/onlinepubs/9699919799/functions/isdigit.html