scripts: kernel-doc: fix typedef parsing

The include/linux/genalloc.h file defined this typedef:

	typedef unsigned long (*genpool_algo_t)(unsigned long *map,unsigned long size,unsigned long start,unsigned int nr,void *data, struct gen_pool *pool, unsigned long start_addr);

Because it has a type composite of two words (unsigned long),
the parser gets the typedef name wrong:

.. c:macro:: long

   **Typedef**: Allocation callback function type definition

Fix the regex in order to accept composite types when
defining a typedef for a function pointer.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/328e8018041cc44f7a1684e57f8d111230761c4f.1603792384.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -1434,13 +1434,14 @@ sub dump_typedef($$) {
     $x =~ s@/\*.*?\*/@@gos;	# strip comments.
 
     # Parse function prototypes
-    if ($x =~ /typedef\s+(\w+)\s*\(\*\s*(\w\S+)\s*\)\s*\((.*)\);/ ||
-	$x =~ /typedef\s+(\w+)\s*(\w\S+)\s*\s*\((.*)\);/) {
+    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
 	$return_type = $1;
 	$declaration_name = $2;
 	my $args = $3;
+	$return_type =~ s/^\s+//;
 
 	create_parameterlist($args, ',', $file, $declaration_name);