Improve ./configure script to fix macOS function detection issues

I made slight improvements to the ./configure file for macOS.

Since I got a MacBook, I have been unable to compile the code with the current ./configure setup. The script could not properly detect some functions, such as sincos and exp10. After some trial and error, I found that these changes fix the problem.

Additionally, note the modifications for __exp10 and __exp10f.

Any feedback or suggestions for further improvements are more than welcome!