boost macros use non-portable tac

[Peter Johansson]

Hi,

I noticed that some AX_BOOST macros now [1] depend on 'tac', which is 
not portable. In particular we experience problem on OSX and found the 
best solution was to downgrade the macros. As one of the major point 
with Autoconf is to have a portable shell script 'configure', it seems 
odd to add dependency to something like 'tac'. It is, of course, 
debatable which tools are standard and not, but in an official archive 
like this, I think it would make sense to follow the GNU Coding Standard 
[2] and only use tools listed there: awk cat cmp cp diff echo egrep expr 
false grep install-info ln ls mkdir mv printf pwd rm rmdir sed sleep 
sort tar test touch tr true.

Any opinions?

Cheers,
Peter


[1] http://savannah.gnu.org/patch/index.php?7816
[2] http://www.gnu.org/prep/standards/standards.html#Utilities-in-Makefiles