fix purego build errors on non-supported architectures

agent/gpu_nvml_unsupported.go

@@ -1,9 +1,21 @@
-//go:build !linux && !windows
+//go:build (!linux && !windows) || (!amd64 && !arm64)
 
 package agent
 
 import "fmt"
 
+type nvmlCollector struct {
+	gm *GPUManager
+}
+
+func (c *nvmlCollector) init() error {
+	return fmt.Errorf("nvml not supported on this platform")
+}
+
+func (c *nvmlCollector) start() {}
+
+func (c *nvmlCollector) collect() {}
+
 func openLibrary(name string) (uintptr, error) {
 	return 0, fmt.Errorf("nvml not supported on this platform")
 }