gnu: erlang: Delete the bootstrap phase.

This fails for the erlang package, as the gnu build system attempts to execute
the bootstrap directory.

* gnu/packages/erlang.scm (erlang)[arguments]: Delete the bootstrap phase.

gnu/packages/erlang.scm

@@ -89,6 +89,7 @@ (define-public erlang
                   (guix build gnu-build-system))
        #:phases
        (modify-phases %standard-phases
+         (delete 'bootstrap)
          ;; The are several code fragments that embed timestamps into the
          ;; output. Here, we alter those fragments to use the value of
          ;; SOURCE_DATE_EPOCH instead.