Reduce the number of NaClLog() calls in the syscall path
Reduce the number of NaClLog() calls in the syscall path

This reduces the overhead of NaCl syscalls.

We only need 2 log messages.  Before, sp_user was logged twice but
isn't very useful.  The address of the syscall handler function isn't
useful either.

As a result, the log is much more readable. For example:

Entering syscall 2: return address 0x263a00020040
Returning from syscall 2: return value 0 (0x0)

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3280
TEST=jump count from run_signal_handler_single_step_test

Review URL: https://codereview.chromium.org/12186009

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@10701 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client