android: fix NODE_PATH needed for rn-bridge

safeGetenv() was changed in nodejs/node@3f61940
so now on Android it's returning undefined. With NODE_PATH as
undefined, then custom nodejs-mobile-react-native builtins such as
don't get found by the cjs loader, which means rn-bridge isn't found.

However, it seems like we can safely get NODE_PATH from process.env
because NODE_PATH is explicitly overwritten by
nodejs-mobile-react-native, so it's not possible that it would take
other values by third parties.

lib/internal/modules/cjs/loader.js

@@ -1383,7 +1383,7 @@ Module.createRequire = createRequire;
 
 Module._initPaths = function() {
   const homeDir = isWindows ? process.env.USERPROFILE : safeGetenv('HOME');
-  const nodePath = isWindows ? process.env.NODE_PATH : safeGetenv('NODE_PATH');
+  const nodePath = process.env.NODE_PATH; // nodejs-mobile patch
 
   // process.execPath is $PREFIX/bin/node except on Windows where it is
   // $PREFIX\node.exe where $PREFIX is the root of the Node.js installation.