msi: Make sure that the target root directory has a trailing backslash.
[wine] / dlls / d3dx10_36 /
drwxr-xr-x   ..
-rw-r--r-- 96 Makefile.in
-rw-r--r-- 16802 d3dx10_36.spec
-rw-r--r-- 1743 d3dx10_36_main.c
-rw-r--r-- 1091 version.rc