drcachesim failures on Mac: config path wrong and pipe ASSERT

The lib suffix is wrong:

```
# bin32/drrun -t drcachesim -- ~/derek/dr/test/hello
ERROR: tracer library ~/derek/dr/git/build_x86_dbg/bin32/../clients/lib32/debug/libdrmemtrace.so is unreadable
```

Pipe behavior is different in more ways than what's already been fixed:

```
# clients/bin32/drcachesim -dr_debug -dr -tracer clients/lib32/debug/libdrmemtrace.dylib -- ~/derek/dr/test/hello

sizeof(long long)=8, x64 is 1311768467750060323
sizeof(_Bool) = 1, sizeof(meow) = 1
b=true, b2=false
Hello world!
Goodbye world!
x is 0x100000000

ASSERT FAILURE: ~/derek/dr/git/src/clients/drcachesim/tracer/tracer.cpp:145: false ()---- ----
```