testing: enforce -skip and -run in example tests

The go test flags -skip and -run had no effect in example tests.

Fixes #61482

Author: mauri870

src/testing/example.go

@@ -6,7 +6,6 @@ package testing
 
 import (
 	"fmt"
-	"os"
 	"sort"
 	"strings"
 	"time"
@@ -29,14 +28,11 @@ func RunExamples(matchString func(pat, str string) (bool, error), examples []Int
 func runExamples(matchString func(pat, str string) (bool, error), examples []InternalExample) (ran, ok bool) {
 	ok = true
 
-	var eg InternalExample
+	m := newMatcher(matchString, *match, "-test.run", *skip)
 
+	var eg InternalExample
 	for _, eg = range examples {
-		matched, err := matchString(*match, eg.Name)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "testing: invalid regexp for -test.run: %s\n", err)
-			os.Exit(1)
-		}
+		_, matched, _ := m.fullName(nil, eg.Name)
 		if !matched {
 			continue
 		}