[MIPS] Implementation of sel_ldr for MIPS architecture.

src/trusted/service_runtime/nacl_syscall_handlers_gen.py

Index: src/trusted/service_runtime/nacl_syscall_handlers_gen.py
diff --git a/src/trusted/service_runtime/nacl_syscall_handlers_gen.py b/src/trusted/service_runtime/nacl_syscall_handlers_gen.py
index 7f5671207737c87b4bbc64cbe6c7bf80fd823e67..7d9b16726662fe687afc555a8e8d0b985701e4c0 100755
--- a/src/trusted/service_runtime/nacl_syscall_handlers_gen.py
+++ b/src/trusted/service_runtime/nacl_syscall_handlers_gen.py
@@ -83,6 +83,8 @@ ARG_REGISTERS = {
     # more untrusted stack space / memory/cache bandwidth, but we had
     # to save these arguments somewhere, either in a processor context
     # or on-stack, anyway.
+    'mips-32': [],
+    # 'mips-32': [ 'a0',  'a1',  'a2',  'a3'],
     }
 
 # Our syscall handling code, in nacl_syscall.S, always pushes the