This allows the compiler to automatically identify which string functions
can be compiled into libraries, and the compiler's internal implementation
is faster than libc functions.
Signed-off-by: anjiahao <anjiahao@xiaomi.com>
remove reference to non-existent readme in libc.
Pointing to the documentation page doesn't make sense in this case,
because it doesn't explain the use of `#undef XXX` for this case anyway.
Signed-off-by: raiden00pl <raiden00@railab.me>
