cmake: fixes for windows

cmake/example.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "../include/core/SkCanvas.h"
 #include "../include/core/SkData.h"
 #include "../include/core/SkSurface.h"
@@ skipping 42 matching lines @@
 static std::shared_ptr<SkSurface> create_opengl_surface(int w, int h) {
     std::cout << "Using opengl surface" << std::endl;
     std::shared_ptr<GrContext> grContext = adopt(GrContext::Create(kOpenGL_GrBackend, 0));
     return adopt(SkSurface::MakeRenderTarget(grContext.get(),
                                             SkBudgeted::kNo,
                                             SkImageInfo::MakeN32Premul(w,h)).release());
 }
 
 int main(int, char**) {
     bool gl_ok = setup_gl_context();
-    srand(time(nullptr));
+    srand((unsigned)time(nullptr));
     std::shared_ptr<SkSurface> surface = (gl_ok && rand() % 2) ? create_opengl_surface(320, 240)
                                                                : create_raster_surface(320, 240);
 
     // Create a left-to-right green-to-purple gradient shader.
     SkPoint pts[] = { {0,0}, {320,240} };
     SkColor colors[] = { 0xFF00FF00, 0xFFFF00FF };
     // Our text will draw with this paint: size 24, antialiased, with the shader.
     SkPaint paint;
     paint.setTextSize(24);
     paint.setAntiAlias(true);
@@ skipping 11 matching lines @@
     std::shared_ptr<SkData> png = adopt(image->encode(SkImageEncoder::kPNG_Type, 100));
 
     // This code is no longer Skia-specific.  We just dump the .png to disk.  Any way works.
     static const char* path = "example.png";
     std::ofstream(path, std::ios::out | std::ios::binary)
         .write((const char*)png->data(), png->size());
     std::cout << "Wrote " << path << std::endl;
 
     return 0;
 }