Ensure syscall functions are consistently prefixed with "NaClSys"

Ensure syscall functions are consistently prefixed with "NaClSys"

Rename NaClTextSysDyncode*() to NaClSysDyncode*() to match the syscall
names.

Rename NaClSetBreak() to NaClSysBrk().  Rename the syscall from
"sysbrk" to "brk" so that the TCB function doesn't have to be called
NaClSysSysBrk(), which would be odd.  "brk" is at least consistent
with Linux's syscall of the same name.

BUG=none
TEST=build

Committed: https://src.chromium.org/viewvc/native_client?view=rev&revision=10736

[bradn, 2013-02-07 01:07:25]

lgtm