Fix issue installing empty database directory

The CMake code to install the empty database directory doesn't appear to
do anything.  Further, it is causing build issues for some users.

Instead of running code to make the directory, it appears we can just
install a directory directly.

Fixes: #1142

freshclam/CMakeLists.txt

@@ -47,7 +47,11 @@ else()
 endif()
 
 # Install an empty database directory
-INSTALL(CODE "FILE(MAKE_DIRECTORY \${ENV}\${CMAKE_INSTALL_PREFIX}/\${DATABASE_DIRECTORY})" COMPONENT programs)
+if(IS_ABSOLUTE ${DATABASE_DIRECTORY})
+    INSTALL(DIRECTORY DESTINATION $ENV{DESTDIR}${DATABASE_DIRECTORY} COMPONENT programs)
+else()
+    INSTALL(DIRECTORY DESTINATION $ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/${DATABASE_DIRECTORY} COMPONENT programs)
+endif()
 
 # Now we rename freshclam-bin executable to freshclam using target properties
 set_target_properties( freshclam-bin