bwctl: build against homebrew's i2util

Closes Homebrew/homebrew#40059.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Formula/bwctl.rb

@@ -1,5 +1,3 @@
-require "formula"
-
 class Bwctl < Formula
   homepage "http://software.internet2.edu/bwctl/"
   url "http://software.internet2.edu/sources/bwctl/bwctl-1.5.4.tar.gz"
@@ -17,10 +15,16 @@ class Bwctl < Formula
   depends_on "thrulay" => :optional
 
   def install
+    # configure mis-sets CFLAGS for I2util
+    # https://lists.internet2.edu/sympa/arc/perfsonar-user/2015-04/msg00016.html
+    # https://github.com/Homebrew/homebrew/pull/38212
+    inreplace "configure", 'CFLAGS="-I$I2util_dir/include $CFLAGS"', 'CFLAGS="-I$with_I2util/include $CFLAGS"'
+
     system "./configure", "--disable-debug",
                           "--disable-dependency-tracking",
                           "--prefix=#{prefix}",
-                          "--mandir=#{man}"
+                          "--mandir=#{man}",
+                          "--with-I2util=#{Formula["i2util"].opt_prefix}"
     system "make", "install"
   end