kernel-doc: handle #if in enums as well

In addition to #ifdef, #define and #endif, also handle
any #if since we may be using e.g. #if IS_ENABLED(...).

I didn't find any instances of this in the kernel now,
there are enums with such ifs inside, but I didn't find
any with kernel-doc as well. However, it came up as we
were adding such a construct in our driver and warnings
from kernel-doc were the result.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240214142937.80ee86a3beae.Ibcc5bd97a20cd10a792663e4b254cd46c7e8b520@changeid

Author: jmberg-intel

scripts/kernel-doc

@@ -1328,7 +1328,7 @@ sub dump_enum($$) {
 
     $x =~ s@/\*.*?\*/@@gos;	# strip comments.
     # strip #define macros inside enums
-    $x =~ s@#\s*((define|ifdef)\s+|endif)[^;]*;@@gos;
+    $x =~ s@#\s*((define|ifdef|if)\s+|endif)[^;]*;@@gos;
 
     if ($x =~ /typedef\s+enum\s*\{(.*)\}\s*(\w*)\s*;/) {
         $declaration_name = $2;