Fix html_dir_files in droiddoc.mk
Fix html_dir_files in droiddoc.mk

Previously html_dir_files includes every file in $(LOCAL_PATH), if
$(LOCAL_DROIDDOC_HTML_DIR) isn't set.

Change-Id: I3c249e5f4a0f52f71edd92862361c1dc4ab6bed7

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build