[build] Avoid confusing sparse in single-argument DBG() macros

For visual consistency with surrounding lines, the definitions of
DBG_MORE(), DBG_PAUSE(), etc include an unnecessary ##__VA_ARGS__
argument which is always elided.  This confuses sparse, which
complains about DBG_MORE_IF() being called with more than one
argument.

Work around this problem by adding an unused variable argument list to
the single-argument macros DBG_MORE_IF() and DBG_PAUSE_IF().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/compiler.h

  *
  * @v level		Debug level
  */
-#define DBG_PAUSE_IF( level ) do {				\
+#define DBG_PAUSE_IF( level, ... ) do {				\
 		if ( DBG_ ## level ) {				\
 			dbg_pause();				\
 		}						\
  *
  * @v level		Debug level
  */
-#define DBG_MORE_IF( level ) do {				\
+#define DBG_MORE_IF( level, ... ) do {				\
 		if ( DBG_ ## level ) {				\
 			dbg_more();				\
 		}						\