Add support for Clang21 (#483)

Author: Twon

.conan/profiles/clang/21/compiler

@@ -0,0 +1,7 @@
+include(../../compiler/clang)
+
+[settings]
+compiler.version=21
+
+[conf]
+tools.build:compiler_executables={"c":"clang-21","cpp":"clang++-21"}

.conan/profiles/clang/21/x64-libc++-debug

@@ -0,0 +1,7 @@
+include(../../default)
+include(../../arch/x64)
+include(../../config/debug)
+include(../../os/current)
+include(../../packages/settings)
+include(compiler)
+include(../../cpp/23)

.conan/profiles/clang/21/x64-libc++-msr

@@ -0,0 +1,7 @@
+include(../../default)
+include(../../arch/x64)
+include(../../config/min-size-rel)
+include(../../os/current)
+include(../../packages/settings)
+include(compiler)
+include(../../cpp/23)

.conan/profiles/clang/21/x64-libc++-release

@@ -0,0 +1,7 @@
+include(../../default)
+include(../../arch/x64)
+include(../../config/release)
+include(../../os/current)
+include(../../packages/settings)
+include(compiler)
+include(../../cpp/23)

.conan/profiles/clang/21/x64-libc++-rwdi

@@ -0,0 +1,7 @@
+include(../../default)
+include(../../arch/x64)
+include(../../config/rel-with-deb-info)
+include(../../os/current)
+include(../../packages/settings)
+include(compiler)
+include(../../cpp/23)

.github/workflows/cmake.yml

@@ -141,6 +141,20 @@ jobs:
                 },
               lib: "libc++",
             }
+          - {
+              name: "Ubuntu Clang-21 + libc++",
+              os: ubuntu-latest,
+              compiler:
+                {
+                  type: CLANG,
+                  version: 21,
+                  conan: "clang",
+                  cc: "clang-21",
+                  cxx: "clang++-21",
+                  std: 23
+                },
+              lib: "libc++",
+            }
           - {
               name: "Visual Studio 2019",
               os: windows-latest,