解决skia静态库中关于jpeg/png编码解码器的全局变量的问题

近期在研究Andriod的图形渲染系统skia，编译好skia后，写了一个小小的测试程序

#include "SkBitmap.h"
#include "SkDevice.h"
#include "SkPaint.h"
#include "gm.h"
#include "SkRect.h"
#include "SkImageEncoder.h"
int main(int argc, char * const argv[])
{
// Declare a raster bitmap, which has an integer width and height,
// and a format (config), and a pointer to the actual pixels.
// Bitmaps can be drawn into a SkCanvas, but they are also used to
// specify the target of a SkCanvas' drawing operations.
SkBitmap bitmap;
bitmap.setConfig(SkBitmap::kARGB_8888_Config, 200, 200);
bitmap.allocPixels();
// A Canvas encapsulates all of the state about drawing into a
// device (bitmap).  This includes a reference to the device itself,
// and a stack of matrix/clip values. For any given draw call (e.g.
// drawRect), the geometry of the object being drawn is transformed
// by the concatenation of all the matrices in the stack. The
// transformed geometry is clipped by the intersection of all of the
// clips in the stack.
SkCanvas canvas(new SkDevice(bitmap));
// SkPaint class holds the style and color information about how to
// draw geometries, text and bitmaps.
SkPaint paint;
// SkIRect holds four 32 bit integer coordinates for a rectangle.
SkRect r;
paint.setARGB(255, 255, 0, 0);
r.set(25, 25, 145, 145);
canvas.drawRect(r, paint); /** Draw the specified rectangle using
  the specified paint. The rectangle
  will be filled or stroked based on
  the Style in the paint. */
paint.setARGB(255, 0, 255, 0);
r.offset(20, 20);
canvas.drawRect(r, paint);
paint.setARGB(255, 0, 0, 255);
r.offset(20, 20);
canvas.drawRect(r, paint);
// SkImageEncoder is the base class for encoding compressed images
// from a specific SkBitmap.
bool bret =false;
bret = SkImageEncoder::EncodeFile("E:\\snapshot.jpg", bitmap,
SkImageEncoder::kJPEG_Type,
/* Quality ranges from 0..100 */ 100);
return 0;
}