Arch Linux

You should add:

sed -i -e 's/automake-1.11/automake-1.14/g' \
-e 's/aclocal-1.11/aclocal-1.14/g' autogen.sh

otherwise it can't be build in updated system

Upadate.

Branch master set up to track remote branch master from origin.
Switched to a new branch 'master'
Switched to a new branch 'new'
Removing themes/Small/gtkrc
Removing themes/Default/gtkrc
Auto-merging plug-ins/common/web-page.c
Auto-merging plug-ins/common/file-svg.c
Auto-merging plug-ins/common/Makefile.am
Removing libgimpwidgets/gimpunitmenu.h
Removing libgimpwidgets/gimpunitmenu.c
Removing libgimpwidgets/gimppixmap.h
Removing libgimpwidgets/gimppixmap.c
Removing libgimpwidgets/gimpoldwidgets.h
Removing libgimpwidgets/gimpoldwidgets.c
Removing etc/gtkrc
Auto-merging configure.ac
CONFLICT (content): Merge conflict in configure.ac
Removing app/widgets/gtkwrapbox.h
Removing app/widgets/gtkwrapbox.c
Removing app/widgets/gtkhwrapbox.h
Removing app/widgets/gtkhwrapbox.c
Auto-merging app/widgets/gimpthumbbox.c
Auto-merging app/widgets/gimpspinscale.c
Auto-merging app/sanity.c
Automatic merge failed; fix conflicts and then commit the result.
==> ERROR: A failure occurred in build().
Aborting...

Use:
https://aur.archlinux.org/packages/babl-devel-git/ and
https://aur.archlinux.org/packages/gegl-devel-git/

gtk3>=3.4.0

Question: what version of gtk use this devel version, because you not list the gtk dependenci for this one