Minor const fixes for overzealous warnings (#883)

examples/opengl2_example/imgui_impl_glfw.cpp

@@ -76,9 +76,9 @@ void ImGui_ImplGlfw_RenderDrawLists(ImDrawData* draw_data)
         const ImDrawList* cmd_list = draw_data->CmdLists[n];
         const ImDrawVert* vtx_buffer = cmd_list->VtxBuffer.Data;
         const ImDrawIdx* idx_buffer = cmd_list->IdxBuffer.Data;
-        glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)((char*)vtx_buffer + OFFSETOF(ImDrawVert, pos)));
-        glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)((char*)vtx_buffer + OFFSETOF(ImDrawVert, uv)));
-        glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (void*)((char*)vtx_buffer + OFFSETOF(ImDrawVert, col)));
+        glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((char*)vtx_buffer + OFFSETOF(ImDrawVert, pos)));
+        glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((char*)vtx_buffer + OFFSETOF(ImDrawVert, uv)));
+        glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((char*)vtx_buffer + OFFSETOF(ImDrawVert, col)));
 
         for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
         {

examples/opengl3_example/imgui_impl_glfw_gl3.cpp

@@ -90,10 +90,10 @@ void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
         const ImDrawIdx* idx_buffer_offset = 0;
 
         glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
-        glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.Size * sizeof(ImDrawVert), (GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW);
+        glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.Size * sizeof(ImDrawVert), (const GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW);
 
         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_ElementsHandle);
-        glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx), (GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW);
+        glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx), (const GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW);
 
         for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
         {