message: Fix gcc 7.2 release warnings about unitialized vars in stbtt_pack_context
diff: @@ -1554,6 +1554,7 @@ bool ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
  // Start packing
  const int max_tex_height = 1024*32;
  stbtt_pack_context spc;
  + memset(&spc, 0, sizeof(spc));
  stbtt_PackBegin(&spc, NULL, atlas->TexWidth, max_tex_height, 0, atlas->TexGlyphPadding, NULL);
  stbtt_PackSetOversampling(&spc, 1, 1);
  