Series-based resizing would be faster if implemented directly
Handle fixed-point overflow in GM fixed
Small memory leak in GIF, probably in libgif
Use libjpeg-turbo for static x86 builds
BMP RLE support
BMP OS/2 format support
bmp/gif tests fail if PNG support is not built

Tests:
  width/height all formats
  keep_aspect, both width/height padding
  Corrupt/invalid files in all formats, triggering longjmp's
  memory_limit
  PNG <8-bit gray

In buildme.sh static build script, could comment out optional libjpeg features to reduce library size:
  DCT_IFAST_SUPPORTED
  DCT_FLOAT_SUPPORTED (benchmark integer vs float DCT)
  INPUT_SMOOTHING_SUPPORTED
  C_PROGRESSIVE_SUPPORTED (we won't write progressive JPEG files)
  C_MULTISCAN_FILES_SUPPORTED (won't write them)
  BLOCK_SMOOTHING_SUPPORTED
  QUANT_1PASS_SUPPORTED
  QUANT_2PASS_SUPPORTED
  
Various PNG defines too, see pngconf.h