[PATCH] A couple minor changes to support sanitizers on FreeBSD 9.2

[Alexey Samsonov]

  Do I understand correctly that this problem will fire on *any* program that is:
  a) compiled with Clang on FreeBSD 9.2
  b) includes stddef.h (i.e. Clang's header)
  c) includes sys/types.h

  it seems impractical to force all FreeBSD users provide -D_SIZE_T_DECLARED. Can we work around this issue in Clang's stddef.h instead? E.g. use:
    #undef size_t
    typedef __SIZE_TYPE__ size_t;
    #define _SIZE_T_DECLARED

http://llvm-reviews.chandlerc.com/D3031