fix(#159): prevent buf to be freed by the GC before resize function exits

.gitignore

@@ -6,3 +6,4 @@ bin
 /*.webp
 /fixtures/*_out.*
 /.idea/
+fixtures/test_vertical_*.jpg

resize.go

@@ -9,15 +9,16 @@ import "C"
 import (
 	"errors"
 	"math"
+	"runtime"
 )
 
 // Resize is used to transform a given image as byte buffer
 // with the passed options.
 func Resize(buf []byte, o Options) ([]byte, error) {
 	defer C.vips_thread_shutdown()
+	defer runtime.KeepAlive(buf)
 
 	image, imageType, err := loadImage(buf)
-
 	if err != nil {
 		return nil, err
 	}