updated for version 7.4.251
Problem:    Crash when BufAdd autocommand wipes out the buffer.
Solution:   Check for buffer to still be valid. Postpone freeing the buffer
	    structure. (Hirohito Higashi)
Added tag v7-4-251 for changeset 29eb4c2a33ac
updated for version 7.4.252
Problem:    Critical error in GTK, removing timer twice.
Solution:   Clear the timer after removing it. (James McCoy)
Added tag v7-4-252 for changeset a43a8262e1ce
updated for version 7.4.253
Problem:    Crash when using cpp syntax file with pattern using external
	    match. (Havard Garnes)
Solution:   Discard match when end column is before start column.
Added tag v7-4-253 for changeset 4901a36479f2
updated for version 7.4.254
Problem:    Smack support detection is incomplete.
Solution:   Check for attr/xattr.h and specific macro.
Added tag v7-4-254 for changeset 251acc686ca4
updated for version 7.4.255
Problem:    Configure check for smack doesn't work with all shells. (David
	    Larson)
Solution:   Remove spaces in set command.
Added tag v7-4-255 for changeset 5595506b985a
updated for version 7.4.256
Problem:    Using systemlist() may cause a crash and does not handle NUL
	    characters properly.
Solution:   Increase the reference count, allocate memory by length. (Yasuhiro
	    Matsumoto)
Added tag v7-4-256 for changeset afb542ea210c