{clang,gcc}_multi: remove manual throws

This avoids hacky workarounds in CI when generating attrpaths for
non-x86_64-linux platforms.

Evaluation for these two attributes will not succeed on platforms other
than Linux anyway, because:
- The unsupported system error from `glibc-nolibgcc` is propagated.
- `pkgsi686Linux.gcc` triggers an assert anyway.

pkgs/top-level/all-packages.nix

@@ -5041,42 +5041,36 @@ with pkgs;
 
   wrapCCMulti =
     cc:
-    if stdenv.targetPlatform.system == "x86_64-linux" then
-      let
-        # Binutils with glibc multi
-        bintools = cc.bintools.override {
-          libc = glibc_multi;
-        };
-      in
-      lowPrio (wrapCCWith {
-        cc = cc.cc.override {
-          stdenv = overrideCC stdenv (wrapCCWith {
-            cc = cc.cc;
-            inherit bintools;
-            libc = glibc_multi;
-          });
-          profiledCompiler = false;
-          enableMultilib = true;
-        };
+    let
+      # Binutils with glibc multi
+      bintools = cc.bintools.override {
         libc = glibc_multi;
-        inherit bintools;
-        extraBuildCommands = ''
-          echo "dontMoveLib64=1" >> $out/nix-support/setup-hook
-        '';
-      })
-    else
-      throw "Multilib ${cc.name} not supported for ‘${stdenv.targetPlatform.system}’";
+      };
+    in
+    lowPrio (wrapCCWith {
+      cc = cc.cc.override {
+        stdenv = overrideCC stdenv (wrapCCWith {
+          cc = cc.cc;
+          inherit bintools;
+          libc = glibc_multi;
+        });
+        profiledCompiler = false;
+        enableMultilib = true;
+      };
+      libc = glibc_multi;
+      inherit bintools;
+      extraBuildCommands = ''
+        echo "dontMoveLib64=1" >> $out/nix-support/setup-hook
+      '';
+    });
 
   wrapClangMulti =
     clang:
-    if stdenv.targetPlatform.system == "x86_64-linux" then
-      callPackage ../development/compilers/llvm/multi.nix {
-        inherit clang;
-        gcc32 = pkgsi686Linux.gcc;
-        gcc64 = pkgs.gcc;
-      }
-    else
-      throw "Multilib ${clang.cc.name} not supported for '${stdenv.targetPlatform.system}'";
+    callPackage ../development/compilers/llvm/multi.nix {
+      inherit clang;
+      gcc32 = pkgsi686Linux.gcc;
+      gcc64 = pkgs.gcc;
+    };
 
   gcc_multi = wrapCCMulti gcc;
   clang_multi = wrapClangMulti clang;