Make socketcan backend compile on pre 3.6 kernels

The CanFD implementation was introduced by the Linux 3.6 kernel.
This change makes the socketcan backend compile on the older Linux
kernel build platforms.

If a socketcan backend was compiled against the most recent kernel
headers but run on an ancient kernel, the missing support is
dynamically detected by virtue of returned error code from
ioctl et al.

Task-number: QTBUG-51932
Change-Id: I5c3601877fa6e882f24d7fa3588dae473a325b9b
Reviewed-by: Rolf Eike Beer <eb@emlix.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/config.tests/socketcan_fd/main.cpp b/config.tests/socketcan_fd/main.cpp
index d499f4b..966c390 100644
--- a/config.tests/socketcan_fd/main.cpp
+++ b/config.tests/socketcan_fd/main.cpp
@@ -39,6 +39,9 @@
 int main()
 {
     canfd_frame frame;
+    int fd_payload = CANFD_MAX_DLEN;
+    fd_payload = CAN_RAW_FD_FRAMES;
+    fd_payload = CANFD_MTU;
     return 0;
 }