contrib: use gcrypt for gnutls on OSX too

contrib/TODO

-binary package creation/downloading/extraction (prebuilt contribs)
+binary package downloading/extraction (prebuilt contribs)
 
 ### Software that fails to build on MacOSX intel
 
-        for 64 bits only:
-nettle
-    undefined symbols when making lib
-
-
-        for 32 bits only:
-
-gmp
-    tmp-dive_1.s:108:junk `@GOT' after expression
-
-
-        for 32 and 64 bits
-
 SDL_image
     Undefined symbols (missing OpenGL framework?)
 
@@ -27,10 +14,8 @@ gnutls, gpg-error
 live555
     use old libtool options (/usr/bin/libtool), we use GNU
 
-
 ### Missing software for MacOSX (was present in extras/contrib)
 
-
 # These 3 are binary framework downloads : no source code is used
 BGHUDAppKit
 Growl           -- last free version: 1.3.0: http://code.google.com/p/growl/source/list http://itunes.apple.com/us/app/growl/id467939042

contrib/src/gnutls/rules.mak

@@ -32,7 +32,15 @@ GNUTLS_CONF := \
 	--disable-guile \
 	$(HOSTCONF)
 
+USE_GCRYPT=0
 ifdef HAVE_WIN32
+USE_GCRYPT=1
+endif
+ifdef HAVE_MACOSX
+USE_GCRYPT=1
+endif
+
+ifeq (1,$(USE_GCRYPT))
 GNUTLS_CONF += --with-libgcrypt
 DEPS_gnutls = gcrypt $(DEPS_gcrypt)
 else