ZSTD_maxCLevel now limited to 21 for 32-bit binaries.

CI tests for constrained memory runs with max level on 32-bit binaries.

.github/workflows/dev-short-tests.yml

@@ -30,6 +30,8 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: make check on 32-bit
+      env:
+        CHECK_CONSTRAINED_MEM: true
       run: |
         sudo apt update
         APT_PACKAGES="gcc-multilib" make apt-install