Apply the patch libgpg-error-1.7.patch to libgpg-error sources. Then run the configuration and installation steps.
./configure CC=xlc CFLAGS="-qchars=signed -qascii -q64 -qlanglvl=extc99 -qexportall -qrent -qnocsect -W l,DLL -D_XOPEN_SOURCE=600 -D_ENHANCED_ASCII_EXT=0xFFFFFFFF -D_IEEEV1_COMPATIBILITY -D_OPEN_MSGQ_EXT" LD=xlc LDFLAGS="-qascii -q64 -W l,DLL" CXX=xlc++ --enable-shared --prefix=/usr/local
make && make check
(as root) make install
Follow the instructions above to turn the archive library into a dynamically linked library.