file.c: move lseek and llseek parsers to a separate file

* lseek.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* file.c: Move sys_lseek, sys_llseek, and related code to lseek.c.
diff --git a/Makefile.am b/Makefile.am
index 0c03252..47b90a2 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -43,6 +43,7 @@
 	ldt.c		\
 	link.c		\
 	loop.c		\
+	lseek.c		\
 	mem.c		\
 	mknod.c		\
 	mount.c		\