flac: disable ogg unless explicitly requested

Fixes Homebrew/homebrew#27349.

Formula/flac.rb

@@ -30,13 +30,20 @@ class Flac < Formula
     ENV.append 'CFLAGS', '-std=gnu89'
 
     # sadly the asm optimisations won't compile since Leopard
-    system "./configure", "--disable-dependency-tracking",
-                          "--disable-debug",
-                          "--disable-asm-optimizations",
-                          "--enable-sse",
-                          "--enable-static",
-                          "--prefix=#{prefix}",
-                          "--mandir=#{man}"
+    args = %W[
+      --disable-dependency-tracking
+      --disable-debug
+      --prefix=#{prefix}
+      --mandir=#{man}
+      --disable-asm-optimizations
+      --enable-sse
+      --enable-static
+    ]
+
+    args << "--without-ogg" if build.without? "libogg"
+
+    system "./configure", *args
+
     ENV['OBJ_FORMAT']='macho'
 
     # adds universal flags to the generated libtool script