Move syslog parser to a separate file

* syslog.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* system.c: Move sys_syslog and related code to syslog.c.
diff --git a/Makefile.am b/Makefile.am
index d6968c0..a87f4a5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -57,6 +57,7 @@
 	syscall.c	\
 	sysctl.c	\
 	sysinfo.c	\
+	syslog.c	\
 	sysmips.c	\
 	system.c	\
 	term.c		\