locale.h:
    Make other locales actually work

math.h:
    exp
    exp2
    expml
    log
    log10
    log2
    log1p
    pow
    cbrt
    hypot
    atan2
    erf
    erfc
    tgamma
    lgamma
    frexp
    ldexp
    M_PI
    M_E
    M_LOG2
    M_LOG10
    other stuff?

stdio.h:
    Basically everything

stdlib.h:
    qsort
    Better PRNG
    Probably other stuff

threads.h:
    Make _Thread_local work on windows
    TODO: add todo items

tgmath.h:
    Basically everything

uchar.h:
    Basically everything

wchar.h:
    Basically everything