syscall: replace strcpy() by g_strlcpy()

linux-user/syscall.c:9860:17: warning: Call to function 'strcpy' is insecure as it does not provide bounding of the memory buffer. Replace unbounded copy functions with analogous functions that support length arguments such as 'strlcpy'. CWE-119
                strcpy (buf->machine, cpu_to_uname_machine(cpu_env));
                ^~~~~~

Reported-by: Clang Static Analyzer
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20170724182751.18261-32-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/syscall.c

@@ -10156,7 +10156,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
             if (!is_error(ret)) {
                 /* Overwrite the native machine name with whatever is being
                    emulated. */
-                strcpy (buf->machine, cpu_to_uname_machine(cpu_env));
+                g_strlcpy(buf->machine, cpu_to_uname_machine(cpu_env),
+                          sizeof(buf->machine));
                 /* Allow the user to override the reported release.  */
                 if (qemu_uname_release && *qemu_uname_release) {
                     g_strlcpy(buf->release, qemu_uname_release,