.github/compilers/workflows.yml: support GCC-11

GCC 11.1 was released. https://gcc.gnu.org/pipermail/gcc/2021-April/235922.html

See also https://github.com/ruby/ruby-ci-image/pull/1

.github/workflows/compilers.yml

@@ -6,7 +6,7 @@ on: [push, pull_request]
 # environment variables (plus the "echo ::set-env" hack) is to reroute that
 # restriction.
 env:
-  default_cc: clang-11
+  default_cc: clang-13
   append_cc: ''
   crosshost: ''
 
@@ -47,33 +47,34 @@ jobs:
       fail-fast: false
       matrix:
         entry:
-          - { key: default_cc, name: gcc-10,    value: gcc-10 }
-#         - { key: default_cc, name: gcc-9,     value: gcc-9 }
-#         - { key: default_cc, name: gcc-8,     value: gcc-8 }
-#         - { key: default_cc, name: gcc-7,     value: gcc-7 }
-#         - { key: default_cc, name: gcc-6,     value: gcc-6 }
-#         - { key: default_cc, name: gcc-5,     value: gcc-5 }
-          - { key: default_cc, name: gcc-4.8,   value: gcc-4.8 }
-          - { key: default_cc, name: clang-13,  value: clang-13 }
-#         - { key: default_cc, name: clang-12,  value: clang-12 }
-#         - { key: default_cc, name: clang-11,  value: clang-11 }
-#         - { key: default_cc, name: clang-10,  value: clang-10 }
-#         - { key: default_cc, name: clang-9,   value: clang-9 }
-#         - { key: default_cc, name: clang-8,   value: clang-8 }
-#         - { key: default_cc, name: clang-7,   value: clang-7 }
-#         - { key: default_cc, name: clang-6.0, value: clang-6.0 }
-#         - { key: default_cc, name: clang-5.0, value: clang-5.0 }
-#         - { key: default_cc, name: clang-4.0, value: clang-4.0 }
-          - { key: default_cc, name: clang-3.9, value: clang-3.9 }
+          - { key: default_cc, name: gcc-11,    value: gcc-11,    container: gcc-11 }
+          - { key: default_cc, name: gcc-10,    value: gcc-10,    container: gcc-10 }
+          - { key: default_cc, name: gcc-9,     value: gcc-9,     container: gcc-9 }
+          - { key: default_cc, name: gcc-8,     value: gcc-8,     container: gcc-8 }
+          - { key: default_cc, name: gcc-7,     value: gcc-7,     container: gcc-7 }
+          - { key: default_cc, name: gcc-6,     value: gcc-6,     container: gcc-6 }
+          - { key: default_cc, name: gcc-5,     value: gcc-5,     container: gcc-5 }
+          - { key: default_cc, name: gcc-4.8,   value: gcc-4.8,   container: gcc-4.8 }
+          - { key: default_cc, name: clang-13,  value: clang-13,  container: clang-13 }
+          - { key: default_cc, name: clang-12,  value: clang-12,  container: clang-12 }
+          - { key: default_cc, name: clang-11,  value: clang-11,  container: clang-11 }
+          - { key: default_cc, name: clang-10,  value: clang-10,  container: clang-10 }
+          - { key: default_cc, name: clang-9,   value: clang-9,   container: clang-9 }
+          - { key: default_cc, name: clang-8,   value: clang-8,   container: clang-8 }
+          - { key: default_cc, name: clang-7,   value: clang-7,   container: clang-7 }
+          - { key: default_cc, name: clang-6.0, value: clang-6.0, container: clang-6.0 }
+          - { key: default_cc, name: clang-5.0, value: clang-5.0, container: clang-5.0 }
+          - { key: default_cc, name: clang-4.0, value: clang-4.0, container: clang-4.0 }
+          - { key: default_cc, name: clang-3.9, value: clang-3.9, container: clang-3.9 }
 
-          - { key: crosshost, name: aarch64-linux-gnu,     value: aarch64-linux-gnu }
+          - { key: crosshost, name: aarch64-linux-gnu,     value: aarch64-linux-gnu, container: crossbuild-essential-arm64 }
 #         - { key: crosshost, name: arm-linux-gnueabi,     value: arm-linux-gnueabi }
 #         - { key: crosshost, name: arm-linux-gnueabihf,   value: arm-linux-gnueabihf }
 #         - { key: crosshost, name: i686-w64-mingw32,      value: i686-w64-mingw32 }
 #         - { key: crosshost, name: powerpc-linux-gnu,     value: powerpc-linux-gnu }
-          - { key: crosshost, name: powerpc64le-linux-gnu, value: powerpc64le-linux-gnu }
-          - { key: crosshost, name: s390x-linux-gnu,       value: s390x-linux-gnu }
-          - { key: crosshost, name: x86_64-w64-mingw32,    value: x86_64-w64-mingw32 }
+          - { key: crosshost, name: powerpc64le-linux-gnu, value: powerpc64le-linux-gnu, container: crossbuild-essential-ppc64el }
+          - { key: crosshost, name: s390x-linux-gnu,       value: s390x-linux-gnu, container: crossbuild-essential-s390x }
+          - { key: crosshost, name: x86_64-w64-mingw32,    value: x86_64-w64-mingw32, container: mingw-w64 }
 
           - { key: append_cc, name: c99,   value: '-std=c99   -Werror=pedantic -pedantic-errors' }
 #         - { key: append_cc, name: c11,   value: '-std=c11   -Werror=pedantic -pedantic-errors' }
@@ -156,7 +157,7 @@ jobs:
 
     name: ${{ matrix.entry.name }}
     runs-on: ubuntu-latest
-    container: ghcr.io/ruby/ruby-ci-image:latest
+    container: ghcr.io/ruby/ruby-ci-image:${{ matrix.entry.container || 'clang-13' }}
     steps:
       - run: mkdir build
         working-directory: