math: remove long double version of bessel functions from math.h
math: remove long double version of bessel functions from math.h

j0l,j1l,jnl,y0l,j1l,jnl are gnu extensions, bsd and posix do not
have them.
noone seems to use them and there is no plan to implement them any
time soon so we shouldn't declare them in math.h.

chardi/musl,chardi/musl,chardi/musl