samples: cellular: gnss: Add overlay for SUPL

Added a configuration overlay file for building the
sample with SUPL assistance support.

Signed-off-by: Tommi Kangas <tommi.kangas@nordicsemi.no>

Author: tokangas

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -312,6 +312,10 @@ Cellular samples
 
   * Added event handling for events from device mode callback.
 
+* :ref:`gnss_sample` sample:
+
+  * Added the configuration overlay file :file:`overlay-supl.conf` for building the sample with SUPL assistance support.
+
 Cryptography samples
 --------------------
 

samples/cellular/gnss/overlay-supl.conf

@@ -0,0 +1,14 @@
+#
+# Copyright (c) 2023 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# SUPL overlay configuration
+
+# Enable SUPL assistance for GNSS sample
+CONFIG_GNSS_SAMPLE_ASSISTANCE_SUPL=y
+
+# SUPL client library requires that the newlib C library is used
+CONFIG_NEWLIB_LIBC=y
+CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y