Issues with log implementation for Neon

[christophe0606]

vlogq_f32 is used directly to implement the arm_vlog_f32.
But vlogq_f32 being based on Taylor expansion for Neon, it can be used only for a limited range of the argument. So arm_vlog_f32 should not use it directly but apply some scaling when the argument is not in the right range.

[Gao-HaoYuan]

I've conducted some tests, and when the value is very close to 1, there are significant differences in the calculation results. It might be beneficial to pay attention to values close to 1, such as 1.000000119, 1.00000119, and 0.9999911.

This critical issue ：
I extracted the code for vlogq_f32 from CMSIS-DSP, When calculating log(1.000000119), the result is -0 instead of +0.

[christophe0606]

@Gao-HaoYuan I think we should do something like computing log(1.000000119/2) + log(2)

I need to study the Taylor expansion used to find the right bounds for the argument.

[Gao-HaoYuan]

Log_test.zip

@christophe0606
This is a code example that requires modification of the IP and NDK addresses.

I attempted to understand the coefficients of the Taylor expansion in the log, but I couldn't figure out the source of the coefficients in the code. It might be a special value from (x-n) of the Taylor expansion. If I have the time, I will also try to solve this issue.