[Gimp-user] upgrading libpng to => 1.6.25

[Al <alpinekid yahoo com>]

 I'm running ubuntu 16.4, 64bit, and im trying to compile the 2.9.x
latest release from github. I want both 2.8 and 2.9 so I'm not using the
ppa from otto which replaces 2.8.

I build 2.9 in a separate dir and did it successfully about 3 months ago
but now
I"ve got a problem.

I've chased the problem down to the requirement for libpng >= 1.6.25
Ubuntu 16.4 uses 1.2.54.

Ive found a package for this libpng-dev_1.6.26-2ubuntu1_amd64.deb and
have it
installed.
The problem is when I #sudo apt-get install libgs-dev or any of the
following
libgdk-pixbuf2.0-dev libgtk2.0-dev librsvg2-dev  libxft-dev

the apt-pkg system reset the libpng-dev to libpng12-dev because that is
a dependency in each of these packages.
If I dont install these packages the make fails looking for
/usr/share/aclocal/gtk-2.0.m4
and I'm sure that is just the first error.

What is the proper way to  upgrade the libpng-dev to 1.6.26 so I can
compile 2.9.x?

Thanks,


Al