glibc-2.33 fails to build on POWER9

[Tobias Platen]

I tried to build glibc-2.33 on my Talos II (no cross compile here),
it fails because the compiler is likely outdated.

checking if the target machine is at least POWER8... yes
checking if the compiler supports -mno-gnu-attribute... yes
checking if gcc compiles signbit with 128-bit floating point type...
yes
checking if gcc compiles with -mabi=ieeelongdouble and -mlong-double-
128... no
checking for objcopy... objcopy
checking version of objcopy... 2.37, ok
configure: error: ***  The compiler must support -mabi=ieeelongdouble
and -mlongdouble simultaneously.

guix --version shows
guix (GNU Guix) 7c9ad54b0616112c7eea6dd02379616aef206490
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