New code from lwip project

lwip repo:
1204f15 bug #35874 reserved identifier violation, 2nd part
f1c7e73 fixed last commit (copy & paste from patch broke the code)

lwip-contrib repo:
6d4e09e bug #35874 reserved identifier violation, 2nd part in even more files
e4ec905 bug #35874 reserved identifier violation, 2nd part