scripts: kernel-doc: split typedef complex regex

The typedef regex for function prototypes are very complex.
Split them into 3 separate regex and then join them using
qr.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/3a4af999a0d62d4ab9dfae1cdefdfcad93383356.1603792384.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -1427,17 +1427,21 @@ sub dump_enum($$) {
     }
 }
 
+my $typedef_type = qr { ((?:\s+[\w\*]+){1,8})\s* }x;
+my $typedef_ident = qr { \*?\s*(\w\S+)\s* }x;
+my $typedef_args = qr { \s*\((.*)\); }x;
+
+my $typedef1 = qr { typedef$typedef_type\($typedef_ident\)$typedef_args }x;
+my $typedef2 = qr { typedef$typedef_type$typedef_ident$typedef_args }x;
+
 sub dump_typedef($$) {
     my $x = shift;
     my $file = shift;
 
     $x =~ s@/\*.*?\*/@@gos;	# strip comments.
 
-    # Parse function prototypes
-    if ($x =~ /typedef((?:\s+[\w\*]+){1,8})\s*\(\*?\s*(\w\S+)\s*\)\s*\((.*)\);/ ||
-	$x =~ /typedef((?:\s+[\w\*]+\s+){1,8})\s*\*?(\w\S+)\s*\s*\((.*)\);/) {
-
-	# Function typedefs
+    # Parse function typedef prototypes
+    if ($x =~ $typedef1 || $x =~ $typedef2) {
 	$return_type = $1;
 	$declaration_name = $2;
 	my $args = $3;