Make quality improvements

- Write some more unit tests
- memcpy() on ARM is now faster
- Address the Musl complex math FIXME comments
- Some libm funcs like pow() now support setting errno
- Import the latest and greatest math functions from ARM
- Use more accurate atan2f() and log1pf() implementations
- atoi() and atol() will no longer saturate or clobber errno

libc/tinymath/cos.c

@@ -78,7 +78,6 @@ __static_yoink("fdlibm_notice");
 
 /**
  * Returns cosine of 𝑥.
- * @note should take ~5ns
  */
 double cos(double x)
 {