Update buildroot to 2020.08

Supports building with GCC 9.

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
Change-Id: Ieaa3a304ef3e414d0d067072d36e82a2eb2cc0e8
diff --git a/rpi3.xml b/rpi3.xml
index f39a1a7..ca6a311 100644
--- a/rpi3.xml
+++ b/rpi3.xml
@@ -20,7 +20,7 @@
         <project path="optee_examples"       name="linaro-swg/optee_examples.git" />
 
         <!-- Misc gits -->
-        <project path="buildroot"            name="buildroot/buildroot.git"               revision="95942f5fcd35d783a49adce621ccf33480f1c88c" />
+        <project path="buildroot"            name="buildroot/buildroot.git"               revision="refs/tags/2020.08" clone-depth="1" />
         <project path="firmware"             name="raspberrypi/firmware.git"              revision="refs/tags/1.20190401" clone-depth="1" />
         <project path="trusted-firmware-a"   name="TF-A/trusted-firmware-a.git"           revision="refs/tags/v2.2" clone-depth="1" remote="tfo"/>
         <project path="u-boot"               name="u-boot/u-boot.git"                     revision="aac0c29d4b8418c5c78b552070ffeda022b16949" />