Remove code that deletes build directory every time in conda recipe.

Incremental builds are supported now.

Author: insertinterestingnamehere

conda.recipe/bld.bat

@@ -1,10 +1,8 @@
 cd %RECIPE_DIR%
 cd ..
 
-:: Remove the build directory since incremental builds aren't currently supported.
-rd /s /q build
-
 python setup.py install || exit 1
+
 rd /s /q %SP_DIR%\__pycache__
 rd /s /q %SP_DIR%\numpy
 rd /s /q %SP_DIR%\Cython