Log Message:
Update to xrdb-1.0.6. Changes:
Allow specifying multiple paths to --with-cpp and running if none is found
Add README with pointers to mailing lists, bugzilla, & git
Fill in COPYING file with notices from xrdb.c & xrdb.man
Migrate to xorg macros 1.3 & XORG_DEFAULT_OPTIONS
Correct make distcheck and sparse warnings.
Avoid divide by zero crash if DDX mistakenly returns screen size of 0mm.