Revert "tau: builds on musl; re-enabled."

This reverts commit c6bb4b922ea75d0ebc5df9a125aa2be535d197ad.

This is highly unreliable, sometimes builds and sometimes
segfaults rustc. Reproduced on x86_64-musl, ppc64le-musl,
ppc64-musl and ppc-musl.

srcpkgs/tau/template

@@ -14,6 +14,12 @@ homepage="https://gitlab.gnome.org/World/Tau"
 distfiles="https://gitlab.gnome.org/World/Tau/uploads/d7d7fc22a851466768edeace0f3d6b1b/tau-${version}.tar.xz"
 checksum=14551674458d1011cfb06152313b1be647aa4e47a8278f8fde57a754a05206b3
 
+# this sometimes builds and sometimes doesn't, do not
+# reenable unless you can reliably build it every time
+case $XBPS_MACHINE in
+	*-musl) broken="crashes rustc" ;;
+esac
+
 post_install() {
 	vlicense LICENSE
 }