[sanitizer_common] Fix devname_r() return type on !NetBSD

Update the interceptor for devname_r() to account for correct return
types on different platforms.  This function returns int on NetBSD
but char* on FreeBSD/OSX.  Noticed by @krytarowski.

Differential Revision: https://reviews.llvm.org/D56150

llvm-svn: 350228