I have to say, that it is probably easier to do that Andy suggests.
However, if you want to further debug this, change the MAKEOPTS variable in the script from -j2 to -j1 and run the script again. Please capture the output. Then upload the output somewhere (e.g. pastebin) and post the link here.
To redirect the output, you do the following:
/path/to/build_arm_toolchain.sh 2>&1 |tee logfile.txt
BTW: the script compiles and installs the script inside the current working directory. You should really create a new, empty directory somewhere, cd into that directy, and then execute the script from there. It will create the build, src, install in that folder.