Start reducing our reliance on autotools (#9824)

Start reducing our reliance on autotools

This commit updates a few of our CI scripts to build protoc using Bazel
instead of autotools. I also updated the setuptools and Rake build
configs to look for protoc under bazel-bin/ so that they will
preferentially use a Bazel-built protoc binary. The goal is to start
chipping away at our use of autotools in preparation for eventually
dropping autotools support.

kokoro/release/python/macos/config.sh

@@ -25,12 +25,13 @@ function pre_build {
     # Runs in the root directory of this repository.
     pushd protobuf
 
-    # Build protoc
-    ./autogen.sh
-    ./configure
-
-    CXXFLAGS="-std=c++14 -fPIC -g -O2" ./configure
-    make -j8
+    # Build protoc and protobuf libraries
+    use_bazel.sh 5.1.1
+    bazel build //:protoc
+    export PROTOC=$PWD/bazel-bin/protoc
+    mkdir src/.libs
+    ln -s $PWD/bazel-bin/libprotobuf.a src/.libs/libprotobuf.a
+    ln -s $PWD/bazel-bin/libprotobuf_lite.a src/.libs/libprotobuf-lite.a
 
     # Generate python dependencies.
     pushd python

kokoro/release/ruby/linux/ruby/ruby_build.sh

@@ -3,11 +3,10 @@
 set -ex
 
 # Build protoc
-if test ! -e src/protoc; then
-  ./autogen.sh
-  ./configure
-  make -j4
-fi
+use_bazel.sh 5.1.1
+bazel build //:protoc
+cp bazel-bin/protoc src/protoc
+export PROTOC=$PWD/src/protoc
 
 umask 0022
 pushd ruby

kokoro/release/ruby/macos/ruby/ruby_build.sh

@@ -3,11 +3,9 @@
 set -ex
 
 # Build protoc
-if test ! -e src/protoc; then
-  ./autogen.sh
-  ./configure
-  make -j4
-fi
+use_bazel.sh 5.1.1
+bazel build //:protoc
+export PROTOC=$PWD/bazel-bin/protoc
 
 umask 0022
 pushd ruby

ruby/Rakefile

@@ -37,10 +37,12 @@ proto2_protos = %w[
   google/protobuf/compiler/plugin.proto
 ]
 
-if system('../src/protoc --version')
-  protoc_command = '../src/protoc' 
+if !ENV['PROTOC'].nil?
+  protoc_command = ENV['PROTOC']
+elsif system('../src/protoc --version')
+  protoc_command = '../src/protoc'
 else
-  protoc_command = 'protoc' 
+  protoc_command = 'protoc'
 end
 
 genproto_output = []