drivers: hv: dxgkrnl: Add noop do-while to non-DEBUG DXG_TRACE to avoid compiler warnings (Nevuly/WSL2-Rolling-Kernel-Issue#37)

When compiling with no DEBUG, snippets like the following generates a
compiler warning on GCC 15 due to DXG_TRACE being expanded into
nothing, which in turn leads to build failures when WERROR=y.

if (result)
    DXG_TRACE("...");

An example of error message is as follows:

drivers/hv/dxgkrnl/dxgmodule.c: In function ‘dxg_pci_probe_device’:
drivers/hv/dxgkrnl/dxgmodule.c:598:43: error: suggest braces around empty body in an ‘if’ statement [-Werror=empty-body]
  598 |                 DXG_TRACE("err: %d",  ret);

This patch modifies the macro so that it generates a noop do-while
loop, serving as a placeholder statement and silencing the warning.

Signed-off-by: Rong Bao <[email protected]>

Author: CSharperMantle

drivers/hv/dxgkrnl/dxgkrnl.h

@@ -1028,7 +1028,7 @@ void dxgk_validate_ioctls(void);
 
 #else
 
-#define DXG_TRACE(...)
+#define DXG_TRACE(...) do {} while (0)
 #define DXG_ERR(fmt, ...) do {					\
 	dev_err(DXGDEV, "%s: " fmt, __func__, ##__VA_ARGS__);	\
 } while (0)