Provide testcases directory for host cross out (windows) modules

If HOST_CROSS_OUT_TESTCASES is not defined, then a module that
builds for windows and has a test config will attempt to install
the config file to /<module>/<module>.config.

Fixes:
[ 54% 99/183] Copy: /simpleperf_unit_test/x86/simpleperf_unit_test.exeninja: error: mkdir(/simpleperf_unit_test): Permission denied

Test: m simpleperf_unit_test
Change-Id: I07dcecbce9c710b29fec5fbdedc462be3245b578