Prefix all no_mangle symbols with __sunrise_libuser

[roblabla]

We should prefix all our no_mangle symbols to avoid potential conflicts with user libraries. This includes:

• eh_personality
• panic_fmt
• rust_oom
• real_start
• start
• clean_bss
• relocate_self
• module_header (in global_asm)
• init_main_thread
• syscall_inner

[kitlith]

lang items like eh_personality are (afaik) not required to be no_mangle, so those should be trivial to fix -- just remove no_mangle.