rpm: make sure to not include var in the Cellar

Closes Homebrew/homebrew#21751.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/rpm.rb

@@ -46,6 +46,7 @@ class Rpm < Formula
   def install
     args = %W[
         --prefix=#{prefix}
+        --localstatedir=#{var}
         --with-path-cfg=#{etc}/rpm
         --with-extra-path-macros=#{lib}/rpm/macros.*
         --disable-openmp
@@ -58,6 +59,7 @@ class Rpm < Formula
         --with-lua
         --with-syck
         --without-apidocs
+        varprefix=#{var}
     ]
 
     system 'glibtoolize -if' # needs updated ltmain.sh