[build] Fix MacOS binary rpath generation (#4376)

For RPATH on MacOS use '@loader_path' instead of '$ORIGIN' to reference the directory where the executable is located. The latter is the mechanism used on Linux.

I think this was exposed due to newer OS X ignoring $DYLD_LIBRARY_PATH for security reasons.

shared/config.gradle

@@ -37,9 +37,11 @@ nativeUtils.platformConfigs.each {
     if (it.name.contains('windows')) {
         return
     }
-    it.linker.args << '-Wl,-rpath,\'$ORIGIN\''
     if (it.name.contains('osx')) {
+        it.linker.args << '-Wl,-rpath,\'@loader_path\''
         it.linker.args << "-headerpad_max_install_names"
+    } else {
+        it.linker.args << '-Wl,-rpath,\'$ORIGIN\''
     }
 }