tests/docker: gcc-10 based images for ppc64{,le} tests

A newer compiler is needed to build tests for Power10 instructions. As
done for arm64 on c729a99d27, a new '-test-cross' image is created for
ppc64 and ppc64le. As done on 936fda4d77, a test for compiler support
is added to verify that the toolchain in use has '-mpower10'. Finally,
Unused images (docker-power-cross and docker-ppc64-cross) are removed.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210423205757.1752480-2-matheus.ferst@eldorado.org.br>
Message-Id: <20210512102051.12134-27-alex.bennee@linaro.org>

tests/docker/dockerfiles/debian-powerpc-cross.docker

@@ -1,12 +0,0 @@
-#
-# Docker powerpc cross-compiler target
-#
-# This docker target builds on the debian Buster base image.
-#
-FROM qemu/debian10
-
-RUN apt update && \
-    DEBIAN_FRONTEND=noninteractive eatmydata \
-    apt install -y --no-install-recommends \
-        gcc-powerpc-linux-gnu \
-        libc6-dev-powerpc-cross

tests/docker/dockerfiles/debian-powerpc-test-cross.docker

@@ -0,0 +1,17 @@
+#
+# Docker powerpc/ppc64/ppc64le cross-compiler target
+#
+# This docker target builds on the debian Bullseye base image.
+#
+FROM qemu/debian11
+
+RUN apt update && \
+    DEBIAN_FRONTEND=noninteractive eatmydata \
+    apt install -y --no-install-recommends \
+        gcc-powerpc-linux-gnu \
+        libc6-dev-powerpc-cross \
+        gcc-10-powerpc64-linux-gnu \
+        libc6-dev-ppc64-cross \
+        gcc-10-powerpc64le-linux-gnu \
+        libc6-dev-ppc64el-cross
+

tests/docker/dockerfiles/debian-ppc64-cross.docker

@@ -1,11 +0,0 @@
-#
-# Docker ppc64 cross-compiler target
-#
-# This docker target builds on the debian Buster base image.
-FROM qemu/debian10
-
-RUN apt update && \
-    DEBIAN_FRONTEND=noninteractive eatmydata \
-    apt install -y --no-install-recommends \
-       gcc-powerpc64-linux-gnu \
-       libc6-dev-ppc64-cross