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.

include/math.h

@@ -399,14 +399,6 @@ float       ynf(int, float);
 #ifdef _GNU_SOURCE
 long double lgammal_r(long double, int*);
 
-long double j0l(long double);
-long double j1l(long double);
-long double jnl(int, long double);
-
-long double y0l(long double);
-long double y1l(long double);
-long double ynl(int, long double);
-
 void        sincos(double, double*, double*);
 void        sincosf(float, float*, float*);
 void        sincosl(long double, long double*, long double*);