[gentoo-user] Failed builds of kbuild and cdrdao with "undefined reference to `__alloca'"

Hi,

I still have the problem of failed builds due to an
'undefined reference to `__alloca''. I recompiled 
gcc/glibc and I am using linux-4.15.1 (from kernel.org)
with linux-headers 4.15. .

Affected are (at least) cdrdao and kbuild.

For me "alloca" (memory allocation_) seems to be quite fundamental
and if this would really be not availlable I think a lot more
builds would fail...

I am using gcc (Gentoo 7.3.0 p1.0) 7.3.0. I recompiled glibc.
I did https://wiki.gentoo.org/wiki/Upgrading_GCC

What can cause this problem and how can I fix it?

Cheers
Meino