Migrate linux-aarch64 tests away from autotools (#10015)

Autotools support is being deprecated, so this moves some of our kokoro tests to cmake

kokoro/linux/aarch64/cpp_crosscompile_and_run_tests_with_qemu_aarch64.sh

@@ -5,12 +5,9 @@
 
 set -ex
 
-mkdir -p cmake/crossbuild_aarch64
-cd cmake/crossbuild_aarch64
-
 # the build commands are expected to run under dockcross docker image
 # where the CC, CXX and other toolchain variables already point to the crosscompiler
-cmake ..
+cmake .
 make -j8
 
 # check that the resulting test binary is indeed an aarch64 ELF

kokoro/linux/aarch64/dockcross_helpers/run_dockcross_manylinux2014_aarch64.sh

@@ -13,7 +13,11 @@ else
 fi
 
 # Pin the dockcross image since newer versions of the image break the build
-PINNED_DOCKCROSS_IMAGE_VERSION=dockcross/manylinux2014-aarch64:20210803-41e5c69
+# We use an older version of dockcross image that has gcc4.9.4 because it was built
+# before https://github.com/dockcross/dockcross/pull/449
+# Thanks to that, wheel build with this image aren't actually
+# compliant with manylinux2014, but only with manylinux_2_24
+PINNED_DOCKCROSS_IMAGE_VERSION=dockcross/manylinux2014-aarch64:20200929-608e6ac
 
 # running dockcross image without any arguments generates a wrapper
 # scripts that can be used to run commands under the dockcross image

kokoro/linux/aarch64/protoc_crosscompile_aarch64.sh

@@ -4,6 +4,5 @@
 
 set -ex
 
-./autogen.sh
-CXXFLAGS="-fPIC -g -O2" ./configure --host=aarch64
+cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON -Dprotobuf_WITH_ZLIB=0 .
 make -j8

kokoro/linux/aarch64/python_crosscompile_aarch64.sh

@@ -8,13 +8,20 @@ set -ex
 
 PYTHON="/opt/python/cp38-cp38/bin/python"
 
-./autogen.sh
-CXXFLAGS="-fPIC -g -O2" ./configure --host=aarch64
+# Initialize any submodules.
+git submodule update --init --recursive
+
+# Build protoc and libprotobuf
+cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON -Dprotobuf_WITH_ZLIB=0 .
 make -j8
 
+# Copy lib files to the expected location.
+mkdir -p src/.libs
+ln -f *.a src/.libs/
+
 # create a simple shell wrapper that runs crosscompiled protoc under qemu
 echo '#!/bin/bash' >protoc_qemu_wrapper.sh
-echo 'exec qemu-aarch64 "../src/protoc" "$@"' >>protoc_qemu_wrapper.sh
+echo 'exec qemu-aarch64 "../protoc" "$@"' >>protoc_qemu_wrapper.sh
 chmod ugo+x protoc_qemu_wrapper.sh
 
 # PROTOC variable is by build_py step that runs under ./python directory

kokoro/linux/aarch64/python_run_tests_with_qemu_aarch64.sh

@@ -16,7 +16,7 @@ ${PYTHON} -m pip install --user pytest auditwheel
 # we've built the python extension previously with --inplace option
 # so we can just discover all the unittests and run them directly under 
 # the python/ directory.
-LD_LIBRARY_PATH=../src/.libs PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=cpp ${PYTHON} -m pytest google/protobuf
+LD_LIBRARY_PATH=. PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=cpp ${PYTHON} -m pytest google/protobuf
 
 # step 2: run auditwheel show to check that the wheel is manylinux2014 compatible.
 # auditwheel needs to run on wheel's target platform (or under an emulator)