Add legal comment about fdk-aac

Signed-off-by: Timothy Gu <timothygu99@gmail.com>

index.html

@@ -2948,6 +2948,9 @@ endef</pre>
     and the
     <a href="http://www.openssl.org/support/faq.html#LEGAL2">OpenSSL project</a>.
     </p>
+    <p>
+    A similar situation also exists for package fdk-aac.
+    </p>
 </div>
 
 <div class="section">

src/fdk-aac.mk

@@ -1,6 +1,9 @@
 # This file is part of MXE.
 # See index.html for further information.
 
+# WARNING: Like openssl, the license of this package is not compatible with
+# GPL 2+, but it is with LGPL 2.1+. See index.html#potential-legal-issues
+
 PKG             := fdk-aac
 $(PKG)_IGNORE   :=
 $(PKG)_VERSION  := 0.1.3

src/ffmpeg.mk

@@ -11,6 +11,11 @@ $(PKG)_URL      := http://www.ffmpeg.org/releases/$($(PKG)_FILE)
 $(PKG)_URL_2    := http://launchpad.net/ffmpeg/main/$($(PKG)_VERSION)/+download/$($(PKG)_FILE)
 $(PKG)_DEPS     := gcc bzip2 gnutls lame libass libbluray libvpx opencore-amr opus sdl speex theora vo-aacenc vo-amrwbenc vorbis x264 xvidcore yasm zlib
 
+# DO NOT ADD fdk-aac OR openssl SUPPORT.
+# Although they are free softwares, their licenses are not compatible with
+# the GPL, and we'd like to enable GPL in our default ffmpeg build.
+# See index.html#potential-legal-issues
+
 define $(PKG)_UPDATE
     $(WGET) -q -O- 'http://ffmpeg.org/releases/' | \
     $(SED) -n 's,.*ffmpeg-\([0-9][^>]*\)\.tar.*,\1,p' | \