Use standard realloc so FreeBSD Host.cpp can use glibc

To fix building on Debian GNU/kFreeBSD, which uses the FreeBSD kernel
with a GNU userland.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@215134 91177308-0d34-0410-b5e6-96231b3b80d8