updated for version 7.3.1221
Problem:    When build flags change "make distclean" run into a configure
	    error.
Solution:   When CFLAGS changes delete auto/config.cache.  Also avoid adding
	    duplicate text to flags.
Added tag v7-3-1221 for changeset 9f7b92f232d3
Merge with master.
Auto version upgrade (7.3.1221)