fixed test for clang

include/ACGL/OpenGL/Objects/TextureBuffer.hh

@@ -59,7 +59,7 @@ public:
     //! the GL buffer can get changed at any time
     void setBufferObject( SharedBufferObject _pBuffer ) {
         Buffer::setBufferObject( _pBuffer );
-        if (_pBuffer == NULL) {
+        if (!_pBuffer) {
             // detach all buffers:
             glTexBuffer( GL_TEXTURE_BUFFER, mDataType, 0 );
         } else {
@@ -87,7 +87,7 @@ private:
     void bind() {}
 
     void attachBufferToTexture() {
-        if (mBuffer == NULL) {
+        if (!mBuffer) {
             // the buffer was in fact detached
             bindTexture();
             glTexBuffer( GL_TEXTURE_BUFFER, mDataType, 0 );