Merged libgd/gd-libgd into master
Fixed memory overrun bug in gdImageScaleTwoPass

_gdContributionsCalc would compute a window size and then adjust
the left and right positions of the window to make a window within
that size.  However, it was storing the values in the struct *before*
it made the adjustment.  This change fixes that.
Merged in suetanvil/gd-libgd/suetanvil (pull request #12)

Fixed memory overrun bug in gdImageScaleTwoPass