file.c: move chown, fchown, and fchownat parsers to a separate file

* chown.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* file.c (sys_chown, sys_fchownat, sys_fchown): Move to chown.c.
diff --git a/Makefile.am b/Makefile.am
index 664475e..e4b7852 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -23,6 +23,7 @@
 	cacheflush.c	\
 	capability.c	\
 	chmod.c		\
+	chown.c		\
 	count.c		\
 	desc.c		\
 	dirent.c	\