This is output from `defines' version 4.1.1, from your buddies at Newtware!
Fri May 22 20:21:57 METDST 2015
HP-UX blnn728x B.11.31 U ia64 HP-UX
cc = [cc]

"/tmp/def24671.c", line 225502: error #2969: the identifier __VA_ARGS__ can only appear in the replacement lists of variadic macros
  #ifdef __VA_ARGS__
         ^

1 error detected in the compilation of "/tmp/def24671.c".
_BIG_ENDIAN	= 1
_BIND_LIBCALLS	= 1
_DEC_EVAL_METHOD	= 0
_FLT_EVAL_METHOD	= 0
_HPUX_SOURCE	= 1
_ILP32	= 1
_INCLUDE_LONGLONG	= 1
_INLINE_ASM	= 1
_Math_errhandling	= MATH_ERREXCEPT
__BASE_FILE__	= "/tmp/def24671.c"
__DATE__	= "May 22 2015"
__EDG_PTRDIFF_TYPE__	= long
__EDG_SIZE_TYPE__	= unsigned long
__EDG_VERSION__	= 401
__EDG__	= 1
__FILE__	= "/tmp/def24671.c"
__HP_cc	= 62501
__LINE__	= 225227
__SIGNED_CHARS__	= 1
__STDC_EXT__	= 1
__STDC_HOSTED__	= 1
__STDC_IEC_559_COMPLEX__	= 1
__STDC_IEC_559__	= 1
__STDC_VERSION__	= 199901L
__STDC__	= 1
__TIMESTAMP__	= "Fri May 22 20:22:08 2015"
__TIME__	= "20:22:09"
__hpux	= 1
__ia64	= 1
__ia64__	= 1
__unix	= 1

Checking other possibilities; should already be listed above:
__DATE__	= "May 22 2015"
__FILE__	= "/tmp/def24671.c"
__LINE__	= 25
__STDC__	= 1
__TIME__	= "20:22:09"

Sizes of basic variable types:
  sizeof(char)           = 8 bits
  sizeof(short)          = 16 bits
  sizeof(int)            = 32 bits
  sizeof(long)           = 32 bits
  sizeof(long long)      = 64 bits
  sizeof(float)          = 32 bits
  sizeof(double)         = 64 bits
  sizeof(long double)    = 128 bits
  sizeof(char *)         = 32 bits
  sizeof(char (*)(char)) = 32 bits