firefox: --without-wasm-sandboxed-libraries

From [Linux From Scratch][1]:

> Using sandboxed wasm libraries has been moved to all builds instead of
> only mozilla automation builds. It requires extra llvm packages and
> was reported to seriously slow the build. Disable it.

[Fedora is doing the same][2], and [*Firefox 95 on POWER*][3] contains
instructions on how to get it to work.

[1]: https://www.linuxfromscratch.org/blfs/view/svn/xsoft/firefox.html
[2]: https://src.fedoraproject.org/rpms/firefox/blob/rawhide/f/firefox-mozconfig
[3]: https://www.talospace.com/2021/12/firefox-95-on-power.html

firefox.be0

@@ -31,6 +31,7 @@ mee_configure() {
 	ac_add_options --disable-crashreporter
 	ac_add_options --disable-updater
 	ac_add_options --enable-bootstrap
+	ac_add_options --without-wasm-sandboxed-libraries
 	mk_add_options MOZ_MAKE_FLAGS="${BEE_MAKEFLAGS}"
 	mk_add_options MOZ_OBJDIR=$B
 	EOF