[MIPS] Add remaining parts for building tests for MIPS

tests/callingconv_case_by_case/nacl.scons

Index: tests/callingconv_case_by_case/nacl.scons
diff --git a/tests/callingconv_case_by_case/nacl.scons b/tests/callingconv_case_by_case/nacl.scons
index e8b11b00bf192a97ac98fa0579badc5d3e5d76d5..a2ae0d789e840fef1d7e4b5462be5154fb41fbf7 100644
--- a/tests/callingconv_case_by_case/nacl.scons
+++ b/tests/callingconv_case_by_case/nacl.scons
@@ -9,6 +9,10 @@ Import('env')
 if env.Bit('bitcode') and env.Bit('pnacl_generate_pexe'):
   Return()
 
+# TODO(petarj): Add nacl-gcc for MIPS.
+if env.Bit('target_mips32'):
+  Return()
+
 # Case-by-case calling Convention Test for PNaCl and nacl-gcc compatibility.
 
 # We make 4 modules.