PR #644: Verify gcc and g++ version in Kokoro kythe build.

Also remove unused code.

This is an attempt to debug the Kokoro kythe build that is consistently not working [[1]](https://source.cloud.google.com/results/invocations/74ae259f-e375-42c1-a1f5-76d6c99ad49a/targets/foss-fpga-tools%2Fverible_internal%2Fkythe_index_generation/log). It looks like it is using some old compiler or old libstdc++ which results in some of the compile troubles ? At least the compile error messages that reference `usr/include/c++/5/` are suspicious.

So as first step, let's output the gcc version.

Also, while at it, remove some old bazel install code.

GitHub PR #644

Copybara import of the project:

  - 3b0791d Verify gcc and g++ version in Kokoro kythe build. by Henner Zeller <[email protected]>
  - 7242ea3 Merge 3b0791d into 58e17... by Henner Zeller <[email protected]>

Closes #644

PiperOrigin-RevId: 351744957

.github/kokoro/kythe.sh

@@ -41,6 +41,8 @@ which wget
 which unzip
 which tar
 which "$BAZEL" && "$BAZEL" version
+which gcc && gcc -v
+which g++ && g++ -v
 echo "... done."
 
 cd "${TMPDIR}"
@@ -85,35 +87,7 @@ cd "${KOKORO_ARTIFACTS_DIR}/github/verible"
 # or: "$BAZEL" clean
 rm -rf "$HOME/.cache/bazel"
 
-# TODO(hzeller): bazelisk section looks dead/unused.
-# Clean-up in favor of installing a versioned release,
-# like in steps/hostsetup.sh.
-#
-# https://github.com/bazelbuild/bazelisk
-# Downloads bazelisk to ~/bin as `bazel`.
-function set_bazel_outdir {
-  mkdir -p /tmpfs/bazel_output
-  export TEST_TMPDIR=/tmpfs/bazel_output
-}
-
-function install_bazelisk {
-  date
-  case "$(uname -s)" in
-    Darwin) local name=bazelisk-darwin-amd64 ;;
-    Linux)  local name=bazelisk-linux-amd64  ;;
-    *) die "Unknown OS: $(uname -s)" ;;
-  esac
-  mkdir -p "$HOME/bin"
-  wget --no-verbose -O "$HOME/bin/bazel" \
-      "https://github.com/bazelbuild/bazelisk/releases/download/v1.3.0/$name"
-  chmod u+x "$HOME/bin/bazel"
-  if [[ ! ":$PATH:" =~ :"$HOME"/bin/?: ]]; then
-    PATH="$HOME/bin:$PATH"
-  fi
-  set_bazel_outdir
-  date
-}
-
+# Testing
 # Create the kythe output directory
 KYTHE_OUTPUT_DIRECTORY="${KOKORO_ARTIFACTS_DIR}/kythe_output"
 mkdir -p "${KYTHE_OUTPUT_DIRECTORY}"