OK build on armv7h worked:
$this->bbcode_second_pass_code('', '[summers@pocketbeagle glibc]$ ls -l /usr/lib/libc-*.so
-rwxr-xr-x 1 root root 1604104 Jun 9 2019 /usr/lib/libc-2.29.so
[summers@pocketbeagle glibc]$ sudo pacman -U glibc-2.30-2-armv7h.pkg.tar.xz
[sudo] password for summers:
loading packages...
resolving dependencies...
looking for conflicting packages...
Packages (1) glibc-2.30-2
Total Installed Size: 36.64 MiB
Net Upgrade Size: -0.34 MiB
:: Proceed with installation? [Y/n]
(1/1) checking keys in keyring [######################] 100%
(1/1) checking package integrity [######################] 100%
(1/1) loading package files [######################] 100%
(1/1) checking for file conflicts [######################] 100%
(1/1) checking available disk space [######################] 100%
:: Processing package changes...
(1/1) upgrading glibc [######################] 100%
Generating locales...
Generation complete.
:: Running post-transaction hooks...
(1/4) Reloading system manager configuration...
(2/4) Creating temporary files...
(3/4) Arming ConditionNeedsUpdate...
(4/4) Updating the info directory file...
[summers@pocketbeagle glibc]$ ls -l /usr/lib/libc-*.so
-rwxr-xr-x 1 root root 1607312 Dec 15 12:08 /usr/lib/libc-2.30.so
')
I've uploaded the armv8 and armv7h to
https://davidjohnsummers.uk/archarm/glibc/ so if you are happy with unofficial packages you can upgrade using these.