Add backtrace_symbols(_fd)() functions

Author: mkornaukhov

libc-test/semver/linux-gnu.txt

@@ -582,6 +582,8 @@ aio_write
 aiocb
 asctime_r
 backtrace
+backtrace_symbols
+backtrace_symbols_fd
 clock_adjtime
 close_range
 copy_file_range

src/unix/linux_like/linux/gnu/mod.rs

@@ -1192,6 +1192,8 @@ extern "C" {
 
     pub fn ctermid(s: *mut c_char) -> *mut c_char;
     pub fn backtrace(buf: *mut *mut c_void, sz: c_int) -> c_int;
+    pub fn backtrace_symbols(buffer: *const *mut c_void, len: c_int) -> *mut *mut c_char;
+    pub fn backtrace_symbols_fd(buffer: *const *mut c_void, len: c_int, fd: c_int);
     #[cfg_attr(gnu_time_bits64, link_name = "__glob64_time64")]
     pub fn glob64(
         pattern: *const c_char,