Add clock_adjtime() to linux-gnu

Author: dfoxfranke

libc-test/semver/linux-gnu.txt

@@ -525,6 +525,7 @@ __rlimit_resource_t
 __timeval
 adjtimex
 backtrace
+clock_adjtime
 copy_file_range
 dlinfo
 dlmopen

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

@@ -1223,6 +1223,8 @@ extern "C" {
     pub fn ntp_adjtime(buf: *mut timex) -> ::c_int;
     #[link_name = "ntp_gettimex"]
     pub fn ntp_gettime(buf: *mut ntptimeval) -> ::c_int;
+    pub fn clock_adjtime(clk_id: ::clockid_t, buf: *mut ::timex) -> ::c_int;
+
     pub fn copy_file_range(
         fd_in: ::c_int,
         off_in: *mut ::off64_t,