This is output from `defines' version 4.1.1, from your buddies at Newtware!
Fri Nov 24 08:01:47 HKT 2012
sysname=XENIX
nodename=(empty)
release=2.3.4
version=SysV
machine=i80386
origin=3
oem=3000
serial#=556257
cc = [gcc]

M_BITFIELDS	= 1 
M_I386	= 1 
M_I86	= 1 
M_I86SM	= 1 
M_SDATA	= 1 
M_STEXT	= 1 
M_SYS3	= 1 
M_SYS5	= 1 
M_SYSIII	= 1 
M_SYSV	= 1 
M_WORDSWAP	= 1 
M_XENIX	= 1 
M_XOUT	= 1 
__BASE_FILE__	= "/tmp/def408.c"
__DATE__	= "Nov 24 2012"
__FILE__	= "/tmp/def408.c"
__GNUC__	= 1 
__INCLUDE_LEVEL__	= 0
__LINE__	= 4583
__STDC__	= 1
__TIME__	= "08:01:47"
__VERSION__	= "1.40"
i386	= 1 
unix	= 1 

Checking other possibilities; should already be listed above:
__DATE__	= "Nov 24 2012"
__FILE__	= "/tmp/def408.c"
__GNUC__	= 1
__LINE__	= 25
__STDC__	= 1
__TIME__	= "08:01:48"

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