Connected sanitizer libraries to the build (for x86)

[Kurt Lidl]

This apparently breaks the build when compiling on a
system that has WITHOUT_IPFILTER= in /etc/src.conf:

--- depend_subdir_libclang_rt ---
In file included from 
/usr/src/lib/libclang_rt/asan/../../../contrib/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.cc:59:
/usr/obj/usr/src/tmp/usr/include/sys/timeb.h:42:2: warning: "this file 
includes <sys/timeb.h> which is deprecated" [-W#warnings]
#warning "this file includes <sys/timeb.h> which is deprecated"
  ^
/usr/src/lib/libclang_rt/asan/../../../contrib/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.cc:100:11: 
fatal error: 'netinet/ip_compat.h' file not found
# include <netinet/ip_compat.h>
           ^
-Kurt