win ninja: include .pdb in linker outputs

This is "just more correct" (will e.g. make -t clean work a bit
better) and also allows syzygy rules that process .pdbs to work.

BUG=chromium:325815
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/126443004

git-svn-id: http://gyp.googlecode.com/svn/trunk@1832 78cadc50-ecff-11dd-a971-7dbc132099af