doc: modernize other GL::Buffer-related snippets also.

doc/snippets/GL.cpp

@@ -329,12 +329,10 @@ struct Foo {
     void setSomeBuffer(GLuint) {}
     GLuint someBuffer() { return {}; }
 } externalLib;
-char someData[1];
 /* [opengl-wrapping-transfer] */
 /* Transferring the instance to external library */
 {
-    GL::Buffer buffer;
-    buffer.setData(someData, GL::BufferUsage::StaticDraw);
+    GL::Buffer buffer = DOXYGEN_ELLIPSIS(GL::Buffer{});
     GLuint id = buffer.release();
     externalLib.setSomeBuffer(id); /* The library is responsible for deletion */
 }

doc/snippets/MeshTools-gl.cpp

@@ -158,12 +158,9 @@ UnsignedInt indexStart, indexEnd;
 std::tie(indexData, indexType, indexStart, indexEnd) =
     MeshTools::compressIndices(indices);
 
-GL::Buffer indexBuffer;
-indexBuffer.setData(indexData, GL::BufferUsage::StaticDraw);
-
 GL::Mesh mesh;
 mesh.setCount(indices.size())
-    .setIndexBuffer(indexBuffer, 0, indexType, indexStart, indexEnd);
+    .setIndexBuffer(GL::Buffer{indexData}, 0, indexType, indexStart, indexEnd);
 /* [compressIndices-stl] */
 }
 CORRADE_IGNORE_DEPRECATED_POP