tce-load -i compiletc ilmbase-dev

cd openexr-2.3.0

CC="gcc -flto -fuse-linker-plugin -march=i486 -mtune=i686 -Os -pipe" CXX="g++ -flto -fuse-linker-plugin -march=i486 -mtune=i686 -Os -pipe" ./configure --prefix=/usr/local --disable-static --localstatedir=/var

find . -name Makefile -type f -exec sed -i 's/-g -O2//g' {} \;

make [2m 20.71s]
sudo make install

Summary for OpenEXR features:

build IlmImf example program                    no
build IlmImf damaged input resilience test      no
build IlmImf huge input test                    no
enable large stack optimizations                yes
internal library namespace                      Imf_2_3
user-client namespace                           Imf