Bug 1697614 - Update mingw builds to clang-12. r=firefox-build-system-reviewers,mhentges

Credit goes to dmajor since he's the one who started this.

Differential Revision: https://phabricator.services.mozilla.com/D113331

taskcluster/ci/toolchain/clang.yml

@@ -50,22 +50,22 @@ linux64-clang-7:
             - linux64-gcc-7
             - linux64-toolchain-sysroot
 
-linux64-clang-11-mingw-x86:
-    description: "MinGW-Clang 11 x86 toolchain build"
+linux64-clang-12-mingw-x86:
+    description: "MinGW-Clang 12 x86 toolchain build"
     treeherder:
         symbol: TMW(clang-x86)
     run:
         script: build-clang-mingw.sh
         arguments:
             - 'x86'
-            - 'build/build-clang/clang-11-mingw.json'
+            - 'build/build-clang/clang-12-mingw.json'
         resources:
-            - 'build/build-clang/clang-11-mingw.json'
+            - 'build/build-clang/clang-12-mingw.json'
         toolchain-alias: linux64-clang-mingw-x86
         toolchain-artifact: public/build/clangmingw.tar.zst
     fetches:
         fetch:
-            - clang-11
+            - clang-12
             - mingw-w64
             - libunwind
             - llvm-mingw
@@ -75,8 +75,8 @@ linux64-clang-11-mingw-x86:
             - linux64-binutils
             - linux64-toolchain-sysroot
 
-linux64-clang-11-mingw-x64:
-    description: "MinGW-Clang 11 x64 toolchain build"
+linux64-clang-12-mingw-x64:
+    description: "MinGW-Clang 12 x64 toolchain build"
     treeherder:
         symbol: TMW(clang-x64)
         tier: 1
@@ -84,14 +84,14 @@ linux64-clang-11-mingw-x64:
         script: build-clang-mingw.sh
         arguments:
             - 'x64'
-            - 'build/build-clang/clang-11-mingw.json'
+            - 'build/build-clang/clang-12-mingw.json'
         resources:
-            - 'build/build-clang/clang-11-mingw.json'
+            - 'build/build-clang/clang-12-mingw.json'
         toolchain-alias: linux64-clang-mingw-x64
         toolchain-artifact: public/build/clangmingw.tar.zst
     fetches:
         fetch:
-            - clang-11
+            - clang-12
             - mingw-w64
             - libunwind
             - llvm-mingw