Remove all autotools usage (#10132)

* Bazelfying conformance tests

Adding infrastructure to "Bazelify" languages other than Java and C++

* Delete benchmarks for languages supported by other repositories

* Bazelfying benchmark tests

* Bazelfying python

Use upb's system python rule instead of branching tensorflow

* Bazelfying Ruby

* Bazelfying C#

* Bazelfying Objective-c

* Bazelfying Kokoro mac builds

* Bazelfying Kokoro linux builds

* Deleting all deprecated files from autotools cleanup

This boils down to Makefile.am and tests.sh and all of their remaining references

* Cleanup after PR reorganizing

- Enable 32 bit tests
- Move conformance tests back
- Use select statements to select alternate runtimes
- Add internal prefixes to proto library macros

* Updating READMEs to use bazel instead of autotools.

* Bazelfying Kokoro release builds

* First round of review fixes

* Second round of review fixes

* Third round of review fixes

* Filtering out conformance tests from Bazel on Windows (b/241484899)

* Add version metadata that was previously scraped from configure.ac

* fixing typo from previous fix

* Adding ruby version tests

* Bumping pinned upb version, and adding tests to python CI
diff --git a/csharp/generate_protos.sh b/csharp/generate_protos.sh
index 62ba1a1..d809aa9 100755
--- a/csharp/generate_protos.sh
+++ b/csharp/generate_protos.sh
@@ -11,17 +11,19 @@
 # Protocol buffer compiler to use. If the PROTOC variable is set,
 # use that. Otherwise, probe for expected locations under both
 # Windows and Unix.
+PROTOC_LOCATIONS=(
+  "bazel-bin/protoc"
+  "solution/Debug/protoc.exe"
+  "cmake/build/Debug/protoc.exe"
+  "cmake/build/Release/protoc.exe"
+)
 if [ -z "$PROTOC" ]; then
-  # TODO(jonskeet): Use an array and a for loop instead?
-  if [ -x solution/Debug/protoc.exe ]; then
-    PROTOC=solution/Debug/protoc.exe
-  elif [ -x cmake/build/Debug/protoc.exe ]; then
-    PROTOC=cmake/build/Debug/protoc.exe
-  elif [ -x cmake/build/Release/protoc.exe ]; then
-    PROTOC=cmake/build/Release/protoc.exe
-  elif [ -x src/protoc ]; then
-    PROTOC=src/protoc
-  else
+  for protoc in "${PROTOC_LOCATIONS[@]}"; do
+    if [ -x "$protoc" ]; then
+      PROTOC="$protoc"
+    fi
+  done
+  if [ -z "$PROTOC" ]; then
     echo "Unable to find protocol buffer compiler."
     exit 1
   fi
@@ -75,9 +77,6 @@
 $PROTOC -Iexamples -Isrc --csharp_out=csharp/src/AddressBook \
     examples/addressbook.proto
 
-$PROTOC -Iconformance -Isrc --csharp_out=csharp/src/Google.Protobuf.Conformance \
-    conformance/conformance.proto
-
 # Benchmark protos
 $PROTOC -Ibenchmarks \
   benchmarks/datasets/google_message1/proto3/*.proto \