Ubuntu 16.04 cannot compile commit c4687d920db081f29e93cca8156793d545a827e2

[Uwe Brauer]

Hi

The last master commit I successfully compiled was 3df7d06d from 23th
December. 

Using my usual configuration 
./configure --prefix=/opt/emacs27 --with-x-toolkit=athena --with-mailutils

I obtained the following error with commit 
c4687d920db081f29e93cca8156793d545a827e2

  CC       widget.o
make -C ../admin/charsets all
make[3]: Entering directory '/home/oub/src/emacs/admin/charsets'
make[3]: Nothing to be done for 'all'.
make[3]: Leaving directory '/home/oub/src/emacs/admin/charsets'
make -C ../admin/unidata charscript.el
make[3]: Entering directory '/home/oub/src/emacs/admin/unidata'
make[3]: Nothing to be done for 'charscript.el'.
make[3]: Leaving directory '/home/oub/src/emacs/admin/unidata'
  CCLD     temacs
/usr/bin/ld: cannot find -lpng12
collect2: error: ld returned 1 exit status
Makefile:651: recipe for target 'temacs' failed
make[2]: *** [temacs] Error 1
make[2]: Leaving directory '/home/oub/src/emacs/src'
Makefile:424: recipe for target 'src' failed
make[1]: *** [src] Error 2
make[1]: Leaving directory '/home/oub/src/emacs'
Makefile:1117: recipe for target 'bootstrap' failed
make: *** [bootstrap] Error 2


So png12 is missing, why did compile me tell about it?

Any solution?

Uwe Brauer