glib: disable dtrace

This was apparently lost in a recent update to the glib formula.

See https://trac.macports.org/ticket/30413

Closes Homebrew/homebrew#11977.

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

Formula/glib.rb

@@ -52,9 +52,11 @@ class Glib < Formula
     # -w is said to causes gcc to emit spurious errors for this package
     ENV.enable_warnings if ENV.compiler == :gcc
 
+    # Disable dtrace; see https://trac.macports.org/ticket/30413
     args = %W[
       --disable-maintainer-mode
       --disable-dependency-tracking
+      --disable-dtrace
       --prefix=#{prefix}
     ]