Add gcc+4.8 to travis

.travis.yml

@@ -14,3 +14,7 @@ node_js:
     - "4.0"
     - "4.1"
 script: npm run travis
+addons:
+  apt:
+    packages:
+    - gcc+4.8

src/image/rotate_worker.cpp

@@ -16,11 +16,12 @@ void RotateWorker::Execute () {
     const float nangle = cimg::mod(_degs, 360.0f);
     if (cimg::mod(nangle, 90.0f) != 0) {
         CImg<unsigned char> * res;
+        int channels = _cimg->spectrum();
         size_t oldwidth = _cimg->width(),
                oldheight = _cimg->height();
         try {
             // 2 pixels wider and taller
-            res = new CImg<unsigned char>(oldwidth + 2, oldheight + 2, 1, N_CHANNELS);
+            res = new CImg<unsigned char>(oldwidth + 2, oldheight + 2, 1, channels);
         } catch (CImgException e) {
             SetErrorMessage("Out of memory");
             return;