[MIPS] Add remaining parts for building tests for MIPS

SConstruct

Index: SConstruct
diff --git a/SConstruct b/SConstruct
index 309d6066b7edb1070e430ed06fa8e0ddae821ad8..f0f75bc3d3cfceea2bf9befc333f38662027eb95 100755
--- a/SConstruct
+++ b/SConstruct
@@ -1485,6 +1485,10 @@ def SelUniversalTest(env, name, nexe, sel_universal_flags=None, **kwargs):
   if env.Bit('nacl_glibc') and not env.Bit('nacl_static_link'):
     return []
 
+  # TODO(petarj): Sel_universal hangs on qemu-mips. Enable when fixed.
+  if env.Bit('target_mips32') and env.UsingEmulator():
+    return []
+
   if sel_universal_flags is None:
     sel_universal_flags = []