fix math library in glibc

[qianxichen233]

Looks like we have math library incorrectly handled and many of the files associated the math functions are compiled with wrong version. For example, for fmod function, /sysdeps/ieee754/dbl-64/w_fmod.c are used instead of math/w_fmod.c, while the former one is an empty file; __log functions depends on __ieee754_log but __ieee754_log also depends on __log, causing infinite recursion here. This is also an example of wrong files are chosen for __log or __ieee754_log.

So we need to figure out:

1. which files of the math function are the correct file to compile
2. how to make glibc choose these files to compile