pastebinit: fixup etc location.

Use where we installed `pastebin.d` instead of the location provided in
the script. This shouldn't affect most users.

Closes Homebrew/homebrew#27887.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Formula/pastebinit.rb

@@ -10,6 +10,7 @@ class Pastebinit < Formula
 
   def install
     inreplace "pastebinit", "/usr/bin/python3", Formula["python3"].opt_bin + "python3"
+    inreplace "pastebinit", "/usr/local/etc/pastebin.d", etc + "pastebin.d"
     system "docbook2man", "pastebinit.xml"
     bin.install "pastebinit"
     etc.install "pastebin.d"