Merge pull request rust-lang#3934 from Laura7089/feat/esp-idf-hostname

Add `get_hostname` to esp-idf

(backport <rust-lang#3934>)
(cherry picked from commit 600e1d1)

libc-test/semver/espidf.txt

@@ -0,0 +1,49 @@
+AF_INET6
+AF_UNIX
+FIONBIO
+MSG_CTRUNC
+MSG_DONTROUTE
+MSG_DONTWAIT
+MSG_EOR
+MSG_MORE
+MSG_NOSIGNAL
+MSG_OOB
+MSG_PEEK
+MSG_TRUNC
+MSG_WAITALL
+NSIG
+POLLERR
+POLLHUP
+POLLIN
+POLLOUT
+POLLPRI
+POLLRDBAND
+POLLRDNORM
+POLLWRBAND
+POLLWRNORM
+PTHREAD_STACK_MIN
+SIGABRT
+SIGFPE
+SIGHUP
+SIGILL
+SIGINT
+SIGQUIT
+SIGSEGV
+SIGTERM
+SOL_SOCKET
+cmsghdr
+dirent
+eventfd
+gethostname
+getrandom
+msghdr
+pthread_create
+recvmsg
+sendmsg
+sigset_t
+sockaddr
+sockaddr_in
+sockaddr_in6
+sockaddr_storage
+sockaddr_un
+stat

src/unix/newlib/espidf/mod.rs

@@ -109,6 +109,8 @@ extern "C" {
 
     pub fn getrandom(buf: *mut ::c_void, buflen: ::size_t, flags: ::c_uint) -> ::ssize_t;
 
+    pub fn gethostname(name: *mut ::c_char, namelen: ::ssize_t);
+
     #[link_name = "lwip_sendmsg"]
     pub fn sendmsg(s: ::c_int, msg: *const ::msghdr, flags: ::c_int) -> ::ssize_t;
     #[link_name = "lwip_recvmsg"]