file.c: move utimes, futimesat, utimensat, and osf_utimes parsers to a separate file

* utimes.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* file.c (decode_utimes, sys_utimes, sys_futimesat, sys_utimensat,
sys_osf_utimes): Move to utimes.c.
diff --git a/Makefile.am b/Makefile.am
index ae535d4..5452d00 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -73,6 +73,7 @@
 	umount.c	\
 	util.c		\
 	utime.c		\
+	utimes.c	\
 	v4l2.c		\
 	vsprintf.c	\
 	xattr.c