We remove the macros LOCAL_THEMES_DIR, LOCAL_STYLES_DIR,
LOCAL_ICON_SETS_DIR, and LOCAL_BACKGROUNDS_DIR.
They were only referenced in the Debian patch 54_Debian_wmmacros.diff, which
set them to /usr/local/share/WindowMaker/{Themes,Styles,etc.}.
In a default installation, THEMES_DIR, STYLES_DIR, etc. coincide exactly
with these paths. In a Debian installation (which defaults to /usr/share
instead of /usr/local/share), it seems unlikely that a user would have these
files in both locations.
