Move platform_disable_tracing into its own file.

Prevents link errors resolving the extern "options" when platform.o
gets linked into ssh-agent when building --with-pam.
diff --git a/Makefile.in b/Makefile.in
index 1a2e743..141608b 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -92,13 +92,13 @@
 	kex.o kexdh.o kexgex.o kexecdh.o kexc25519.o \
 	kexdhc.o kexgexc.o kexecdhc.o kexc25519c.o \
 	kexdhs.o kexgexs.o kexecdhs.o kexc25519s.o \
-	platform.o platform-pledge.o
+	platform-pledge.o platform-tracing.o
 
 SSHOBJS= ssh.o readconf.o clientloop.o sshtty.o \
 	sshconnect.o sshconnect1.o sshconnect2.o mux.o
 
 SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o \
-	audit.o audit-bsm.o audit-linux.o \
+	audit.o audit-bsm.o audit-linux.o platform.o \
 	sshpty.o sshlogin.o servconf.o serverloop.o \
 	auth.o auth1.o auth2.o auth-options.o session.o \
 	auth-chall.o auth2-chall.o groupaccess.o \
diff --git a/platform-tracing.c b/platform-tracing.c
new file mode 100644
index 0000000..81020e7
--- /dev/null
+++ b/platform-tracing.c
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2016 Darren Tucker.  All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#if defined(HAVE_SYS_PRCTL_H)
+#include <sys/prctl.h>	/* For prctl() and PR_SET_DUMPABLE */
+#endif
+#ifdef HAVE_PRIV_H
+#include <priv.h> /* For setpflags() and __PROC_PROTECT  */
+#endif
+#include <stdarg.h>
+
+#include "log.h"
+
+void
+platform_disable_tracing(int strict)
+{
+#if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
+	/* Disable ptrace on Linux without sgid bit */
+	if (prctl(PR_SET_DUMPABLE, 0) != 0 && strict)
+		fatal("unable to make the process undumpable");
+#endif
+#if defined(HAVE_SETPFLAGS) && defined(__PROC_PROTECT)
+	/* On Solaris, we should make this process untraceable */
+	if (setpflags(__PROC_PROTECT, 1) != 0 && strict)
+		fatal("unable to make the process untraceable");
+#endif
+}
diff --git a/platform.c b/platform.c
index c68bb09..acf8554 100644
--- a/platform.c
+++ b/platform.c
@@ -18,14 +18,6 @@
 
 #include "includes.h"
 
-#include <sys/types.h>
-#if defined(HAVE_SYS_PRCTL_H)
-#include <sys/prctl.h>	/* For prctl() and PR_SET_DUMPABLE */
-#endif
-#ifdef HAVE_PRIV_H
-#include <priv.h> /* For setpflags() and __PROC_PROTECT  */
-#endif
-
 #include <stdarg.h>
 #include <unistd.h>
 
@@ -223,18 +215,3 @@
 #endif
 	return 0;
 }
-
-void
-platform_disable_tracing(int strict)
-{
-#if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
-	/* Disable ptrace on Linux without sgid bit */
-	if (prctl(PR_SET_DUMPABLE, 0) != 0 && strict)
-		fatal("unable to make the process undumpable");
-#endif
-#if defined(HAVE_SETPFLAGS) && defined(__PROC_PROTECT)
-	/* On Solaris, we should make this process untraceable */
-	if (setpflags(__PROC_PROTECT, 1) != 0 && strict)
-		fatal("unable to make the process untraceable");
-#endif
-}