Build the symbol table after adding each file instead of continually
rebuilding it.

This fixes an issue where functions that require ICU data segfault
the process due to an unexpected lack of ICU data.

The actual ICU data is provided by the icudt71_dat object.

Linking on Linux currently errors with `undefined reference to `'dlsym'`

(including our codespace)

Alpine Linux's `ar` program doesn't support having objects with the
same name in the archive twice, so we have to use the GNU extension
for including paths.

This commit *should* honestly be split into multiple separate commits,
but unfortunately pretty much all of these changes have to be applied
as a unit or a build step fails.

Let node figure out the snake business.