chibi-scheme: deparallelize

Closes Homebrew/homebrew#21593.

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

Formula/chibi-scheme.rb

@@ -7,6 +7,8 @@ class ChibiScheme < Formula
   head 'https://code.google.com/p/chibi-scheme/', :using => :hg
 
   def install
+    ENV.deparallelize
+
     # "make" and "make install" must be done separately
     system "make"
     system "make", "install", "PREFIX=#{prefix}"