Change MIPS to avoid "none-nacl" for unsandboxed tests.

This changes the run-pnacl-sz script to be more consistent
with the other targets.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=4167
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/1232483003 .

Patch from Reed Kotler <reed.kotler@imgtec.com>.
diff --git a/pydir/run-pnacl-sz.py b/pydir/run-pnacl-sz.py
index 72b6a0b..cefd475 100755
--- a/pydir/run-pnacl-sz.py
+++ b/pydir/run-pnacl-sz.py
@@ -19,7 +19,7 @@
   # add here for Mips32.
   flags = { 'x8632': ['-triple=i686'],
             'arm32': ['-triple=armv7a', '-mcpu=cortex-a9', '-mattr=+neon'],
-            'mips32': ['-triple=mipsel-none-nacl' ] }
+            'mips32': ['-triple=mipsel' ] }
   return flags[target]