Auto merge of #3421 - ids1024:redox-group, r=JohnTitor

redox: Add remaining `grp.h` functions

Author: bors

libc-test/semver/redox.txt

@@ -180,6 +180,7 @@ bsearch
 chroot
 clearerr
 difftime
+endgrent
 endpwent
 endservent
 epoll_create
@@ -191,7 +192,10 @@ explicit_bzero
 fchdir
 fmemopen
 getdtablesize
+getgrent
+getgrgid
 getgrgid_r
+getgrnam
 getgrnam_r
 getgrouplist
 getline
@@ -212,6 +216,7 @@ pipe2
 pthread_condattr_setclock
 qsort
 reallocarray
+setgrent
 setpwent
 setrlimit
 setservent

src/unix/redox/mod.rs

@@ -1080,13 +1080,18 @@ extern "C" {
     pub fn getdtablesize() -> ::c_int;
 
     // grp.h
+    pub fn getgrent() -> *mut ::group;
+    pub fn setgrent();
+    pub fn endgrent();
+    pub fn getgrgid(gid: ::gid_t) -> *mut ::group;
     pub fn getgrgid_r(
         gid: ::gid_t,
         grp: *mut ::group,
         buf: *mut ::c_char,
         buflen: ::size_t,
         result: *mut *mut ::group,
     ) -> ::c_int;
+    pub fn getgrnam(name: *const ::c_char) -> *mut ::group;
     pub fn getgrnam_r(
         name: *const ::c_char,
         grp: *mut ::group,