don't crash when compiling with optimizations
don't crash when compiling with optimizations

gcc and clang do NOT take '-nostdlib' to mean 'run without dynamic
libraries'; instead they take it to mean "don't use the standard
library, I'm going to use my own". To actually run without dynamic
libraries you need -ffreestanding.

see https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html,
https://gcc.gnu.org/onlinedocs/gcc/Standards.html, and
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90701 for details.

addresses https://github.com/proot-me/proot-rs/issues/3

vincenthage/proot_rust