ci: remove workaround for Xtensa environment

With [38] tentatively in (through a branched action), [491] can be
reverted; the latter had doing something like [38] in its list of
considered alternatives, but failed to foresee the need for sourcing all
that data back in for compiling C code on Xtensa.

[38]: esp-rs/xtensa-toolchain#38
[491]: ariel-os#491

Author: chrysn

.github/workflows/build.yml

@@ -79,20 +79,6 @@ jobs:
           override: false
           export: false
 
-      - name: Keep general build environment clean of Xtensa peculiarities
-        if: steps.result-cache.outputs.cache-hit != 'true'
-        # The Xtensa setup unconditionally sets LIBCLANG_PATH in GITHUB_ENV --
-        # we can't undo that. (It also sets it in ~/exports, but that is just
-        # what it uses internally to get that data around into the action
-        # script)
-        #
-        # As the shell apparently does not source any files, and until
-        # https://github.com/actions/runner/issues/1126 is fixed by GitHub, the
-        # best remedy is to stow the workaround and source it wherever we can.
-        run: |
-          set -x
-          echo 'unset LIBCLANG_PATH' >> ~/source-this-first.sh
-
       - name: rust cache
         if: steps.result-cache.outputs.cache-hit != 'true'
         uses: Swatinem/rust-cache@v2
@@ -107,7 +93,6 @@ jobs:
       - name: "installing prerequisites"
         if: steps.result-cache.outputs.cache-hit != 'true'
         run: |
-          source ~/source-this-first.sh
           git config --global init.defaultBranch main
           git config --global user.email "ci@riot-labs.de"
           git config --global user.name "CI"
@@ -134,13 +119,11 @@ jobs:
       - name: "limit build unless nightly build"
         if: github.event_name != 'schedule' && steps.result-cache.outputs.cache-hit != 'true'
         run: |
-          source ~/source-this-first.sh
           echo "LAZE_BUILDERS=ai-c3,espressif-esp32-c6-devkitc-1,espressif-esp32-s3-devkitc-1,bbc-microbit-v2,nrf52840dk,nrf5340dk,rpi-pico,rpi-pico-w,st-nucleo-h755zi-q,st-nucleo-wb55" >> "$GITHUB_ENV"
 
       - name: "ariel-os compilation test"
         if: steps.result-cache.outputs.cache-hit != 'true'
         run: |
-          source ~/source-this-first.sh
           sccache --start-server || true # work around https://github.com/ninja-build/ninja/issues/2052
 
           CONFIG_WIFI_NETWORK='test' CONFIG_WIFI_PASSWORD='password' laze build --global --partition hash:${{ matrix.partition }}