A few issues:

* rawmemchr - it might be faster as it doesn't have to decrement the size_t but this only mildly relevant for lwan as many instances of rawmemchr use are simply rawmemchr(ptr, '\0') which is exactly the same as ptr + strlen(ptr) + 1 and even less optimized.

* pthread_tryjoin_np - __linux__ is defined by gcc not glibc, you should check for __GLIBC__ if you want to use glibc specific functions.

* underscore prefixed functions - pedantic I know but it is reserved for the implementation.