I think I have a brutal fix …
After unpacking the ROOT 5.34 source code, edit the “root/config/Makefile.linux” file for the “32-bit / i686 + gcc” target, or the “root/config/Makefile.linuxx8664gcc” file for the “64-bit / x86_64 + gcc” target, and remove the string “-Wl,–no-undefined” from the “LDFLAGS” inside. cd root
sed -i -e '{s/-Wl,--no-undefined //}' config/Makefile.* Then configure and make ROOT as usual.
P.S. The problem is that, if the “-Wl,–no-undefined” option is in force, then the old gcc 3.4.6 would need the “/lib/ld-linux.so.2” for the “32-bit / i686 + gcc” target and the “/lib64/ld-linux-x86-64.so.2” for the “64-bit / x86_64 + gcc” target to be explicitly added to the link command line (e.g. after “-ldl”).