How to install library files

Visit packages.ubuntu.com

In its Search the contents of packages section, search for the file.

It will list the packages that contain particular file.

In your case, these packages are provided by the following packages:

libgtk-x11-2.0.so.0     libgtk2.0-0
libgdk-x11-2.0.so.0     libgtk2.0-0
libgdk_pixbuf-2.0.so.0  libgdk-pixbuf2.0-0
libfontconfig.so.1      libfontconfig1 
libXrender.so.1         libxrender1
libX11.so.6             libx11-6
libgobject-2.0.so.0     libglib2.0-0 
libXft.so.2             libxft2
libfreetype.so.6        libfreetype6
libpthread.so.0         libc6
librt.so.1              libc6
libz.so.1               zlib1g
libpng12.so.0           libpng12-0
libstdc++.so.6          libstdc++6-4.8-dbg-arm64-cross
libm.so.6               libc6
libgcc_s.so.1           libgcc1 
libc.so.6               libc6

So you can install them by:

sudo apt-get install libgtk2.0-0 libgdk-pixbuf2.0-0 libfontconfig1 libxrender1 libx11-6 libglib2.0-0  libxft2 libfreetype6 libc6 zlib1g libpng12-0 libstdc++6-4.8-dbg-arm64-cross libgcc1