Update copyright notices to use Linux Foundation guidance

As a result, the copyright of contributors other than Arm is now
acknowledged, and the years of publishing are no longer tracked in the
source files.

Also remove the now-redundant lines declaring that the files are part of
MbedTLS.

This commit was generated using the following script:

# ========================
#!/bin/sh

# Find files
find '(' -path './.git' -o -path './3rdparty' ')' -prune -o -type f -print | xargs sed -bi '

# Replace copyright attribution line
s/Copyright.*Arm.*/Copyright The Mbed TLS Contributors/I

# Remove redundant declaration and the preceding line
$!N
/This file is part of Mbed TLS/Id
P
D
'
# ========================

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index 421aa11..c24ace4 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -1,7 +1,7 @@
 /*
  *  Benchmark demonstration program
  *
- *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  *
  *  This file is provided under the Apache License 2.0, or the
@@ -42,8 +42,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  *  **********
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
 #if !defined(MBEDTLS_CONFIG_FILE)
diff --git a/programs/test/cpp_dummy_build.cpp b/programs/test/cpp_dummy_build.cpp
index 8f94071..0bd1265 100644
--- a/programs/test/cpp_dummy_build.cpp
+++ b/programs/test/cpp_dummy_build.cpp
@@ -2,7 +2,7 @@
  *  This program is a dummy C++ program to ensure Mbed TLS library header files
  *  can be included and built with a C++ compiler.
  *
- *  Copyright (C) 2018, ARM Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  *
  *  This file is provided under the Apache License 2.0, or the
@@ -43,8 +43,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  *  **********
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
 #if !defined(MBEDTLS_CONFIG_FILE)
diff --git a/programs/test/query_compile_time_config.c b/programs/test/query_compile_time_config.c
index 0d55d5b..4cb23e3 100644
--- a/programs/test/query_compile_time_config.c
+++ b/programs/test/query_compile_time_config.c
@@ -1,7 +1,7 @@
 /*
  *  Query the Mbed TLS compile time configuration
  *
- *  Copyright (C) 2018, Arm Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  *
  *  This file is provided under the Apache License 2.0, or the
@@ -42,8 +42,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  *  **********
- *
- *  This file is part of Mbed TLS (https://tls.mbed.org)
  */
 
 #if !defined(MBEDTLS_CONFIG_FILE)
diff --git a/programs/test/selftest.c b/programs/test/selftest.c
index 006573e..9bc9a9c 100644
--- a/programs/test/selftest.c
+++ b/programs/test/selftest.c
@@ -1,7 +1,7 @@
 /*
  *  Self-test demonstration program
  *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  *
  *  This file is provided under the Apache License 2.0, or the
@@ -42,8 +42,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  *  **********
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
 #if !defined(MBEDTLS_CONFIG_FILE)
diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index 5a4968a..66ead4a 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -1,7 +1,7 @@
 /*
  *  UDP proxy: emulate an unreliable UDP connexion for DTLS testing
  *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  *
  *  This file is provided under the Apache License 2.0, or the
@@ -42,8 +42,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  *  **********
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
 /*
diff --git a/programs/test/udp_proxy_wrapper.sh b/programs/test/udp_proxy_wrapper.sh
index 1d87408..6f68daf 100755
--- a/programs/test/udp_proxy_wrapper.sh
+++ b/programs/test/udp_proxy_wrapper.sh
@@ -2,7 +2,7 @@
 # -*-sh-basic-offset: 4-*-
 # Usage: udp_proxy_wrapper.sh [PROXY_PARAM...] -- [SERVER_PARAM...]
 #
-# Copyright (C) 2017, Arm Limited, All Rights Reserved
+# Copyright The Mbed TLS Contributors
 # SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 #
 # This file is provided under the Apache License 2.0, or the
@@ -43,8 +43,6 @@
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 #
 # **********
-#
-# This file is part of Mbed TLS (https://tls.mbed.org)
 
 set -u
 
diff --git a/programs/test/zeroize.c b/programs/test/zeroize.c
index 5c8f9be..dbc394e 100644
--- a/programs/test/zeroize.c
+++ b/programs/test/zeroize.c
@@ -9,7 +9,7 @@
  * facilities are then used to manually inspect the memory and verify that the
  * call to mbedtls_platform_zeroize() was not eliminated.
  *
- *  Copyright (C) 2018, Arm Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  *
  *  This file is provided under the Apache License 2.0, or the
@@ -50,8 +50,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  *  **********
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
 #if !defined(MBEDTLS_CONFIG_FILE)