Maybe you were not in src folder?
I just checked these on ubuntu:
Code:
sudo apt-get install subversion
(...)
$ svn checkout http://keeperfx.googlecode.com/svn/trunk/keeperfx/ keeperfx-read-only
(...)
$ cd keeperfx-read-only/src
$ grep -Rxe "^[[:space:]]*\(return[[:space:]]*\|\)\_DK\_[[:alnum:]\_]*[(].*[)].*;.*$" *.c | wc -l
563
$ grep -Rxe "^[[:space:]]*\(//return[[:space:]]*\|//\)\_DK\_[[:alnum:]\_]*[(].*[)].*;.*$" *.c | wc -l
415
$
Also, it's possible that the escaping used in the query is specific to BASH.