Import reallocarray(3) from OpenBSD

Add a manpage for it, assign the copyright to the OpenBSD project on it since it
is mostly copy/paste from OpenBSD manpage.
style(9) fixes

Differential Revision:	https://reviews.freebsd.org/D2420
Reviewed by:	kib

1 files changed, 3 insertions, 0 deletions

diff --git a/include/stdlib.h b/include/stdlib.h
index 95db1b3..84587db 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -111,6 +111,9 @@ long double
 	 strtold(const char * __restrict, char ** __restrict);
 unsigned long
 	 strtoul(const char * __restrict, char ** __restrict, int);
+#ifdef __BSD_VISIBLE
+void	*reallocarray(void *, size_t, size_t);
+#endif
 int	 system(const char *);
 int	 wctomb(char *, wchar_t);
 size_t	 wcstombs(char * __restrict, const wchar_t * __restrict, size_t);