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/hikey.xml b/hikey.xml
index 67167c0..87a7437 100644
--- a/hikey.xml
+++ b/hikey.xml
@@ -21,7 +21,7 @@
 
         <!-- Misc gits -->
         <project path="atf-fastboot"         name="96boards-hikey/atf-fastboot.git"       revision="d75cfac3877be68bb5e36be3fc57ba597a2d3710" />
-        <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="burn-boot"            name="96boards-hikey/burn-boot.git"          revision="7dcbfb1f1496756294b3068e6e2370a9399dcea2" />
         <project path="busybox"              name="mirror/busybox.git"                    revision="refs/tags/1_24_0" clone-depth="1" />
         <project path="edk2"                 name="96boards-hikey/edk2.git"               revision="77326b5a153513c826d5a50363eace6ef6b59413" />