scripts/kernel-doc: Do not process backslash lines in comments

To prevent this, do the pre-processing only for lines which are no
comments, e.g. do not start with ' *'.

Suggested-by: Matthew Wilcox <[e-mail]>
Signed-off-by: Anna-Maria Behnsen <[e-mail]>
Tested-by: Randy Dunlap <[e-mail]>
Acked-by: Daniel Vetter <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

scripts/kernel-doc

···
 
     $section_counter = 0;
     while (<IN_FILE>) {
-	while (s/\\\s*$//) {
+	while (!/^ \*/ && s/\\\s*$//) {
 	    $_ .= <IN_FILE>;
 	}
 	# Replace tabs by spaces