[gtk-osx] Fix nettle build on recent clang versions.

[John Ralls <jralls src gnome org>]

commit 8341fd4d3bb8ff11472edcf86bf4744c8f54f3cc
Author: John Ralls <jralls ceridwen us>
Date:   Mon Sep 28 11:30:44 2020 -0700

    Fix nettle build on recent clang versions.
    
    See https://git.lysator.liu.se/nettle/nettle/-/merge_requests/9/diffs

 modulesets-stable/gtk-osx-network.modules   |  1 +
 patches/libnettle-cc-for-build-return.patch | 11 +++++++++++
 2 files changed, 12 insertions(+)
---
diff --git a/modulesets-stable/gtk-osx-network.modules b/modulesets-stable/gtk-osx-network.modules
index 1974a09..84d9159 100644
--- a/modulesets-stable/gtk-osx-network.modules
+++ b/modulesets-stable/gtk-osx-network.modules
@@ -48,6 +48,7 @@
     <branch repo="ftp.gnu.org" version="3.5.1"
             module="nettle/nettle-3.5.1.tar.gz"
             hash="sha256:75cca1998761b02e16f2db56da52992aef622bf55a3b45ec538bc2eedadc9419">
+      <patch 
file="https://gitlab.gnome.org/GNOME/gtk-osx/raw/master/patches/libnettle-cc-for-build-return.patch"; 
strip="1"/>
     </branch>
     <dependencies>
       <dep package="gmp"/>
diff --git a/patches/libnettle-cc-for-build-return.patch b/patches/libnettle-cc-for-build-return.patch
new file mode 100644
index 0000000..b4d1baf
--- /dev/null
+++ b/patches/libnettle-cc-for-build-return.patch
@@ -0,0 +1,11 @@
+--- a/configure        2019-06-26 22:35:06.000000000 -0700
++++ b/configure        2020-09-28 09:14:49.000000000 -0700
+@@ -4638,7 +4638,7 @@
+ int
+ main ()
+ {
+-  exit(0);
++  return(0);
+ }
+ EOF
+ gmp_compile="$CC_FOR_BUILD conftest.c"