Fix filename typo.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@61453 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Sema/dllimmport-dllexport.c b/test/Sema/dllimport-dllexport.c
similarity index 100%
rename from test/Sema/dllimmport-dllexport.c
rename to test/Sema/dllimport-dllexport.c