Subzero: Support non-IRT immediate calls with -filetype=iasm.

pydir/crosstest.py

 #!/usr/bin/env python2
 
 import argparse
 import os
 import subprocess
 import sys
 import tempfile
 
 from utils import shellcmd
 from utils import FindBaseNaCl
@@ skipping 128 matching lines @@
     # Add szrt_sb_x8632.o or szrt_native_x8632.o.
     objs.append((
             '{root}/toolchain_build/src/subzero/build/runtime/' +
             'szrt_{sb}_' + args.target + '.o'
             ).format(root=nacl_root, sb='sb' if args.sandbox else 'native'))
     pure_c = os.path.splitext(args.driver)[1] == '.c'
     # Set compiler to clang, clang++, pnacl-clang, or pnacl-clang++.
     compiler = '{bin}/{prefix}{cc}'.format(
         bin=bindir, prefix='pnacl-' if args.sandbox else '',
         cc='clang' if pure_c else 'clang++')
-    sb_native_args = (['-O0', '--pnacl-allow-native', '-arch', 'x8632']
+    sb_native_args = (['-O0', '--pnacl-allow-native', '-arch', 'x8632',
+                       '-Wn,-defsym=__Sz_AbsoluteZero=0']
                       if args.sandbox else
-                      ['-g', '-m32', '-lm', '-lpthread'])
+                      ['-g', '-m32', '-lm', '-lpthread',
+                       '-Wl,--defsym=__Sz_AbsoluteZero=0'])
     shellcmd([compiler, args.driver] + objs +
              ['-o', os.path.join(args.dir, args.output)] + sb_native_args)
 
 if __name__ == '__main__':
     main()