LibC: Remove i686 support

Author: https://github.com/supercomputer7
Commit: 92da98822a
Pull-request: https://github.com/SerenityOS/serenity/pull/15467
Issue: https://github.com/SerenityOS/serenity/issues/15444
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/fuel-pcbox

Userland/Libraries/LibC/math.cpp

@@ -633,7 +633,7 @@ long double frexpl(long double x, int* exp) NOEXCEPT
     return scalbnl(x, -(*exp));
 }
 
-#if !(ARCH(I386) || ARCH(X86_64))
+#if !(ARCH(X86_64))
 
 double round(double value) NOEXCEPT
 {