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/am57xx.xml b/am57xx.xml
index 6a18130..8e363f0 100644
--- a/am57xx.xml
+++ b/am57xx.xml
@@ -17,7 +17,7 @@
         <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="linux"          name="ti-linux-kernel/ti-linux-kernel.git" revision="00a3beacce33dc14fa301eb5f3fb5a341212e9b4" remote="ti" />
         <project path="u-boot"         name="ti-u-boot/ti-u-boot.git"             revision="c68ed086bd00054e28c46e033385f79104c3f84c" remote="ti" />
 </manifest>