MIPS ptrace build fixes

Since Pedro's ptrace cleanups, the MIPS buildbot compilation fails.
Code in MIPS native uses ptrace with 3 arguments, where ptrace requires
4.  When looking at the definition of ptrace in
/usr/include/sys/ptrace.h, it shows that it takes a variable number of
arguments.  The wrapper macro in nat/gdb_ptrace.h takes a fixed number
of arguments (4).  That would explain why it used to work and stopped.

I am pushing this as obvious, tell me if there is any problem.

I built-tested this with a MIPS toolchain (ct-ng), but I don't have any
setup to test it.  At least it should put back the buildbot builder in a
better shape.

gdb/ChangeLog:

	* mips-linux-nat.c (write_watchpoint_regs): Add NULL as ptrace's 4th
	parameter.
	(mips_linux_new_thread): Likewise.
	* nat/mips-linux-watch.c (mips_linux_read_watch_registers): Likewise.

gdb/gdbserver/ChangeLog:

	* linux-mips-low.c (mips_linux_prepare_to_resume): Add NULL as
	ptrace's 4th parameter.

5 files changed, 16 insertions, 4 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 0c24f0c..8dee2da 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2015-07-29  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* mips-linux-nat.c (write_watchpoint_regs): Add NULL as ptrace's 4th
+	parameter.
+	(mips_linux_new_thread): Likewise.
+	* nat/mips-linux-watch.c (mips_linux_read_watch_registers): Likewise.
+
 2015-07-29  Patrick Palka  <patrick@parcs.ath.cx>
 
 	* top.c: Include "tui/tui.h".
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 5b4236a..2e039b5 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-29  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* linux-mips-low.c (mips_linux_prepare_to_resume): Add NULL as
+	ptrace's 4th parameter.
+
 2015-07-27  Yao Qi  <yao.qi@linaro.org>
 
 	* configure.srv (case aarch64*-*-linux*): Don't set
diff --git a/gdb/gdbserver/linux-mips-low.c b/gdb/gdbserver/linux-mips-low.c
index d3b01d6..770f0df 100644
--- a/gdb/gdbserver/linux-mips-low.c
+++ b/gdb/gdbserver/linux-mips-low.c
@@ -427,7 +427,7 @@ mips_linux_prepare_to_resume (struct lwp_info *lwp)
 	  int tid = ptid_get_lwp (ptid);
 
 	  if (-1 == ptrace (PTRACE_SET_WATCH_REGS, tid,
-			    &priv->watch_mirror))
+			    &priv->watch_mirror, NULL))
 	    perror_with_name ("Couldn't write watch register");
 	}
 
diff --git a/gdb/mips-linux-nat.c b/gdb/mips-linux-nat.c
index 961cb6f..6df618d 100644
--- a/gdb/mips-linux-nat.c
+++ b/gdb/mips-linux-nat.c
@@ -614,7 +614,7 @@ write_watchpoint_regs (void)
   ALL_LWPS (lp)
     {
       tid = ptid_get_lwp (lp->ptid);
-      if (ptrace (PTRACE_SET_WATCH_REGS, tid, &watch_mirror) == -1)
+      if (ptrace (PTRACE_SET_WATCH_REGS, tid, &watch_mirror, NULL) == -1)
 	perror_with_name (_("Couldn't write debug register"));
     }
   return 0;
@@ -634,7 +634,7 @@ mips_linux_new_thread (struct lwp_info *lp)
     return;
 
   tid = ptid_get_lwp (lp->ptid);
-  if (ptrace (PTRACE_SET_WATCH_REGS, tid, &watch_mirror) == -1)
+  if (ptrace (PTRACE_SET_WATCH_REGS, tid, &watch_mirror, NULL) == -1)
     perror_with_name (_("Couldn't write debug register"));
 }
 
diff --git a/gdb/nat/mips-linux-watch.c b/gdb/nat/mips-linux-watch.c
index 02d83f6..231dbe0 100644
--- a/gdb/nat/mips-linux-watch.c
+++ b/gdb/nat/mips-linux-watch.c
@@ -164,7 +164,7 @@ mips_linux_read_watch_registers (long lwpid,
 {
   if (force || *watch_readback_valid == 0)
     {
-      if (ptrace (PTRACE_GET_WATCH_REGS, lwpid, watch_readback) == -1)
+      if (ptrace (PTRACE_GET_WATCH_REGS, lwpid, watch_readback, NULL) == -1)
 	{
 	  *watch_readback_valid = -1;
 	  return 0;