Fix typo

Actually expand the OUTPRE variable instead of just using a literal
string.

(cherry picked from commit 6298655a778e58af6f0faaff554e126378ce7c4a)

https://github.com/krb5/krb5/commit/647ccfc140d4215b0a4d4cf52fc1ab7899dea163
Author: Ben Kaduk <kaduk@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 647ccfc140d4215b0a4d4cf52fc1ab7899dea163
Branch: krb5-1.10
 src/ccapi/lib/win/Makefile.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)