openexr, imlbase: unbreak on macOS

With the default configuration, the libraries are generated with a
-2_4.24.dylib suffix, and linking with -l...-2_4  doesn't work.  Pass
the configure option to turn off the suffix.

pkgs/development/libraries/ilmbase/default.nix

@@ -18,6 +18,9 @@ stdenv.mkDerivation rec {
     ./bootstrap
   '';
 
+  # otherwise, the pkgconfig info for the libraries will not match the filenames
+  configureFlags = stdenv.lib.optionalString stdenv.isDarwin "--enable-namespaceversioning=no";
+  
   depsBuildBuild = [ buildPackages.stdenv.cc ];
   nativeBuildInputs = [ automake autoconf libtool which ];
 

pkgs/development/libraries/openexr/default.nix

@@ -42,6 +42,9 @@ stdenv.mkDerivation rec {
     ./bootstrap
   '';
 
+  # otherwise, the pkgconfig info for the libraries will not match the filenames
+  configureFlags = stdenv.lib.optionalString stdenv.isDarwin "--enable-namespaceversioning=no";
+
   nativeBuildInputs = [ pkgconfig autoconf automake libtool ];
   propagatedBuildInputs = [ ilmbase zlib ];