debuggerd: Fix missing include.

The structure user_vfp is incorrectly defined in bionic/libc/kernel/arch-arm/asm/ptrace.h
at the moment, while it should be under bionic/libc/kernel/arch-arm/asm/user.h instead.

Before moving its definition in the corresponding source files, we need to fix its users.
It happens that debuggerd is the only one for now, so fix this by including <linux/user.h>
instead (which will include <asm/user.h> and <asm/ptrace.h>).

Also, make the debug output less chatty by specifying all symbols to be listed
through XLOG2 instead of XLOG.

Change-Id: I16e0fa700945d86efd44ee885a84ad609c0a9b58
diff --git a/debuggerd/arm/machine.c b/debuggerd/arm/machine.c
index 4eb97a3..e765c3b 100644
--- a/debuggerd/arm/machine.c
+++ b/debuggerd/arm/machine.c
@@ -32,6 +32,7 @@
 #include <cutils/properties.h>
 
 #include <linux/input.h>
+#include <linux/user.h>
 
 #include "utility.h"