There are of course tons of code on the net, but there is no need to standardize another grab-bag of bad API calls. If you need a batteries-included library you use python or similar. If you write in C, you care so much that you largely avoid the standard library and design your code from the ground up.

BSD has some minor improvements to libc. There's also glib.

Generally though, C is just a terrible language to do anything other than write extremely low level routines in. You should probably just never use strtok() and go straight to something like Ragel or re2c for building high performance tokenizers... then call those from a higher level language.