Backport parts of bbea2cd from main

MSYS2's clang32 compiler is deprecated.  Fix distcheck.

.github/workflows/msys2.yml

@@ -21,7 +21,6 @@ jobs:
       matrix:
         include:
           - { msystem: CLANG64, env: clang-x86_64, extra_packages: "mingw-w64-clang-x86_64-clang mingw-w64-clang-x86_64-clang-analyzer" }
-          - { msystem: CLANG32, env: clang-i686,   extra_packages: "mingw-w64-clang-i686-clang mingw-w64-clang-i686-clang-analyzer"     }
           - { msystem: MINGW64, env: x86_64,       extra_packages: "mingw-w64-x86_64-gcc"                                               }
           - { msystem: MINGW32, env: i686,         extra_packages: "mingw-w64-i686-gcc"                                                 }
           # No need to test UCRT64 since clang64 uses UCRT

ci/distcheck.sh

@@ -3,14 +3,9 @@
 # SPDX-License-Identifier: MIT
 set -e
 
-OS=""
-if [ "$TRAVIS_OS_NAME" != "" ]; then
-    OS="$TRAVIS_OS_NAME"
-elif [ "$CIRRUS_OS" != "" ]; then
-    OS="$CIRRUS_OS"
-fi
+OS=`uname -s || true`
 
-if [ "$OS" = "linux" ]; then
+if [ "$OS" = "Linux" ]; then
     # Make distribution tarball
     autoreconf -fi
     ./configure