Building GnuTLS on Mac OS X

gistfile1.md

Preparing the Build Environment

cd ~/Desktop
mkdir wget-build
cd wget-build

Building & Installing GMP 5.0.2

curl -O ftp://ftp.gmplib.org/pub/gmp-5.0.2/gmp-5.0.2.tar.bz2
tar xjf gmp-5.0.2.tar.bz2
pushd gmp-5.0.2
CC=gcc-4.2 CXX=g++4.2 ./configure --prefix=/usr/local
make
sudo make install
popd

Building & Installing Libnettle 2.4

curl -O http://www.lysator.liu.se/~nisse/archive/nettle-2.4.tar.gz
tar xzf nettle-2.4.tar.gz
pushd nettle-2.4
CFLAGS="-m64" ./configure --prefix=/usr/local --disable-assembler
make
sudo make install
popd

Building & Installing GnuTLS 2.12.12

curl -O http://ftp.gnu.org/gnu/gnutls/gnutls-2.12.12.tar.bz2
tar xjf gnutls-2.12.12.tar.bz2
pushd gnutls-2.12.12
CFLAGS="-m64" CXXFLAGS="-m64" ./configure --prefix=/usr/local --without-p11-kit
make
sudo make install
popd

I run into an error when try to make nettle-2.4 on my MacBook with OS 10.11.5:

In file included from /usr/local/include/gmp.h:50:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cstddef:46:9: error: no member named
      'ptrdiff_t' in the global namespace
using ::ptrdiff_t;
      ~~^
1 error generated.

I could compile the previous library (GMP 5.0.2) but I had to install gcc-4.2 through brew, the hint from @jaycode (from 12 Jun 2012) didn't help, there was no more 4.2 on my system, I guess this is too old.
What could I do? I don't understand this error.
Or is there another way to get gnutls on Mac OS 10.11.5?
Thanks

EDIT 2016-07-04: never mind, I let go my plan of compiling inadyn on Mac, where I need gnutls. There are too many other issues anyway.

On mac, you have to change the command: CC=gcc-4.2 CXX=g++4.2 ./configure --prefix=/usr/local
to CC=gcc CXX=g++ ./configure --prefix=/usr/local

With macos 10.12.6, I could install GMP, but not Nettle. After running configure and make, I ran make check. The result was:
88 of 89 tests failed

For one thing, it complained that libhogweed.4.dylib could not be found. I tried to attach the history of my installation attempt (starting with curl), and the output of make check to this post as a file, but every time I tried I got an upload error ("We don't support that file type"), even though I tried txt, zip, and pdf versions of the file. So I created a GH repo where you can view the file, here:

https://github.com/impactanalysts/Nettle-install-fail-on-OSX-10.12.6