Auto merge of #3174 - devnexen:redox_reallocarray, r=JohnTitor

redox reallocarray addition

Author: bors

libc-test/semver/redox.txt

@@ -204,6 +204,7 @@ open_wmemstream
 pipe2
 pthread_condattr_setclock
 qsort
+reallocarray
 setrlimit
 setservent
 strcasecmp

src/unix/redox/mod.rs

@@ -1043,6 +1043,9 @@ extern "C" {
     pub fn pthread_cancel(thread: ::pthread_t) -> ::c_int;
     pub fn pthread_kill(thread: ::pthread_t, sig: ::c_int) -> ::c_int;
 
+    // stdlib.h
+    pub fn reallocarray(ptr: *mut ::c_void, nmemb: ::size_t, size: ::size_t) -> *mut ::c_void;
+
     // string.h
     pub fn strlcat(dst: *mut ::c_char, src: *const ::c_char, siz: ::size_t) -> ::size_t;
     pub fn strlcpy(dst: *mut ::c_char, src: *const ::c_char, siz: ::size_t) -> ::size_t;