Log Message:
Update to libXpm-3.5.8. Changes:

Bug 14171: sxpm/Makefile.am:21: SED was already defined
Add README with pointers to mailing list, bugzilla & git repos
Update AC_DEFINE_DIR to latest version from Autoconf Archive
Replace AC_DEFINE_DIR with AX_DEFINE_DIR from Autoconf Archive
Migrate to xorg macros 1.3 & XORG_DEFAULT_OPTIONS
libXpm 3.5.8
Use libtools SED check rather than autoconf's SED check.
Replace static ChangeLog with dist-hook to generate from git log
nuke RCS Ids
Janitor: ansification, make distcheck, .gitignore
X.Org Bug 17944: avoid gcc warning for libXpm