help with gcc5 install on linux

[Anton Shterenlikht]

I usually use gcc installed by others.
I now tried to install gcc5, and get problems.
Please help.

1. untarred
gfortran.com/download/x86_64/gcc-5-infrastructure.tar.xz
gfortran.com/download/x86_64/nightlies/gcc-trunk-20150202-r220340.tar.xz

2. added gcc5 infrastructure lib64 dir to LD_LIBRARY_PATH

Compilation seems to work, but not linking:

$ ./gcc5/gcc-trunk/bin/gfortran -c z.f90
$ 
$ ./gcc5/gcc-trunk/bin/gfortran z.f90
collect2: fatal error: cannot find 'ld'
compilation terminated.
$
$ which ld
/usr/bin/ld
$

What am I missing?

Thanks

Anton