Load dynamic cpu lib on windows

On linux, we link the CPU library in to the Go app and fall back to it
when no GPU match is found. On windows we do not link in the CPU library
so that we can better control our dependencies for the CLI.  This fixes
the logic so we correctly fallback to the dynamic CPU library
on windows.

llm/shim_ext_server_windows.go

@@ -4,6 +4,7 @@ import (
 	"embed"
 	"log"
 	"os"
+	"path/filepath"
 	"strings"
 )
 
@@ -11,14 +12,20 @@ import (
 var libEmbed embed.FS
 
 func updatePath(dir string) {
+	tmpDir := filepath.Dir(dir)
 	pathComponents := strings.Split(os.Getenv("PATH"), ";")
+	i := 0
 	for _, comp := range pathComponents {
-		// Case incensitive
-		if strings.ToLower(comp) == strings.ToLower(dir) {
+		if strings.EqualFold(comp, dir) {
 			return
 		}
+		// Remove any other prior paths to our temp dir
+		if !strings.HasPrefix(strings.ToLower(comp), strings.ToLower(tmpDir)) {
+			pathComponents[i] = comp
+			i++
+		}
 	}
-	newPath := strings.Join(append(pathComponents, dir), ";")
+	newPath := strings.Join(append([]string{dir}, pathComponents...), ";")
 	log.Printf("Updating PATH to %s", newPath)
 	os.Setenv("PATH", newPath)
 }