Build error in tseries.c on OS X 10.8.2
Just updated OS X to 10.8.2 and Xcode to 4.5. Building pandas (commit 1e68fd9) now fails with an undeclared variable error in some cython code.

```
gcc-4.2 -DNDEBUG -g -Os -Wall -Wstrict-prototypes -pipe -arch x86_64 -I/Library/Python/2.7/site-packages/numpy-1.8.0.dev_9597b1f_20120920-py2.7-macosx-10.8-x86_64.egg/numpy/core/include -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c pandas/src/tseries.c -o build/temp.macosx-10.8-x86_64-2.7/pandas/src/tseries.o
In file included from /Library/Python/2.7/site-packages/numpy-1.8.0.dev_9597b1f_20120920-py2.7-macosx-10.8-x86_64.egg/numpy/core/include/numpy/ndarraytypes.h:1722,
                 from /Library/Python/2.7/site-packages/numpy-1.8.0.dev_9597b1f_20120920-py2.7-macosx-10.8-x86_64.egg/numpy/core/include/numpy/ndarrayobject.h:17,
                 from /Library/Python/2.7/site-packages/numpy-1.8.0.dev_9597b1f_20120920-py2.7-macosx-10.8-x86_64.egg/numpy/core/include/numpy/arrayobject.h:15,
                 from pandas/src/tseries.c:253:
/Library/Python/2.7/site-packages/numpy-1.8.0.dev_9597b1f_20120920-py2.7-macosx-10.8-x86_64.egg/numpy/core/include/numpy/npy_deprecated_api.h:11:2: warning: #warning "Using deprecated NumPy API, disable it by #defining NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION"
pandas/src/tseries.c: In function ‘__pyx_pf_6pandas_3lib_112monthrange’:
pandas/src/tseries.c:48311: error: ‘_days_per_month_table’ undeclared (first use in this function)
pandas/src/tseries.c:48311: error: (Each undeclared identifier is reported only once
pandas/src/tseries.c:48311: error: for each function it appears in.)
error: command 'gcc-4.2' failed with exit status 1
```
