incorrect quoting for windows building in conda?
trying to build master in clean windows x64 miniconda environment, gcc itself is in windows path:

```
writing build\temp.win-amd64-2.7\Release\pandas\index.def
C:\Program Files\mingw-builds\x64-4.8.1-posix-seh-rev5\mingw64\bin\dllwrap.exe -DMS_WIN64 -mdll -static --entry _DllMain@12 --output-lib build\temp.win-amd64-2.7\Release\pandas\libindex.a --def build\temp.win-amd64-2.7\Release\pandas\index.def -s build\temp.win-amd64-2.7\Release\pandas\index.o build\temp.win-amd64-2.7\Release\pandas\src\datetime\np_datetime.o build\temp.win-amd64-2.7\Release\pandas\src\datetime\np_datetime_strings.o -LC:\Miniconda\envs\pandas_dev\libs -LC:\Miniconda\envs\pandas_dev\PCbuild\amd64 -lpython27 -lmsvcr90 -o c:\Dev\src\pandas\pandas\index.pyd
'gcc" "-Wl' is not recognized as an internal or external command,
operable program or batch file.
dllwrap: gcc exited with status 1
error: command 'C:\\Program Files\\mingw-builds\\x64-4.8.1-posix-seh-rev5\\mingw64\\bin\\dllwrap.exe' failed with exit status 1
```
