Build fail for 7.3.0 with in-tree binutils

[Matt Godbolt]

Hi there,

I've been building homegrown GCCs with in-tree binutils (2.29.1) for a long
while, with a pretty simple script. However, with the 7.3 release I'm
seeing:

gcc/7.3.0/objdir/binutils/../../gcc-7.3.0/binutils/dwarf.c:976: undefined
reference to `get_DW_IDX_name'

Has anyone seen this before, and/or does anyone have an idea what I might
be doing wrong?

The script I use is here:
https://github.com/mattgodbolt/compiler-explorer-image/blob/master/gcc/build/build.sh

The same error occurs when I build GCC 5.5, but curiously does not happen
when I grab a trunk build from svn directly.

Thanks in advance!

-- 
Matt