Merge pull request #2787 from emekoi/fix-2768

forward error code in build.zig

std/build.zig

@@ -769,14 +769,14 @@ pub const Builder = struct {
                 if (code != 0) {
                     warn("The following command exited with error code {}:\n", code);
                     printCmd(null, argv);
-                    std.debug.panic("exec failed");
+                    std.os.exit(@truncate(u8, code));
                 }
                 return stdout.toOwnedSlice();
             },
-            else => {
+            .Signal, .Stopped, .Unknown => |code| {
                 warn("The following command terminated unexpectedly:\n");
                 printCmd(null, argv);
-                std.debug.panic("exec failed");
+                std.os.exit(@truncate(u8, code));
             },
         }