acos.s fix: use the formula acos(x) = atan2(sqrt(1-x),sqrt(1+x))
[musl] / src / setjmp /
drwxr-xr-x   ..
drwxr-xr-x - arm
drwxr-xr-x - i386
-rw-r--r-- 0 longjmp.c
-rw-r--r-- 0 setjmp.c
drwxr-xr-x - x86_64