ecasound 2.8.1: Fix ruby support behavior

Change formula to always pass explicit --enable-rubyecasound=<yes|no>
so it works regardless of the ecasound configure's default behavior
for --enable-ruby. Formula was assuming default was no, but default was
actually yes, so the ruby stuff got built even when --with-ruby was
not supplied, which could break the build when attempting to install
in to /Library/Ruby.

Fixes Homebrew/homebrew#19357.
Closes Homebrew/homebrew#19420.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/ecasound.rb

@@ -14,7 +14,8 @@ class Ecasound < Formula
       --disable-dependency-tracking
       --prefix=#{prefix}
     ]
-    args << "--enable-rubyecasound=yes" if build.include? 'with-ruby'
+    # Always explicitly control ruby, since there's some confusion about the default
+    args << ("--enable-rubyecasound=%s" % ((build.include? 'with-ruby') ? 'yes' : 'no'))
     system "./configure", *args
     system "make install"
   end