bug#24256: new module for grep's DFA matcher

[Paul Eggert]

After this change, 'make dist' no longer works on the current Ubuntu version 
(16.04.1 LTS). The failure is as follows. I'm not quite sure how to debug this 
sort of thing, as the syntax checks are a bit twisty. Although this isn't a huge 
obstacle to issuing a new grep release (as one can run 'make dist' on the 
current Fedora version), it's still a bit troublesome.

PS. I updated to the latest gnulib to fix a 'make check' failure on AIX 7.1.

...
space_tab
0.01 space_tab
tight_scope
make[4]: Entering directory '/home/eggert/src/gnu/grep/src'
dfaalloc
dfacomp
dfaexec
dfafree
dfaisfast
dfamust
dfamustfree
dfasuperset
dfasyntax
case_folded_counterparts
init_localeinfo
the above functions should have static scope
/home/eggert/src/gnu/grep/tight-scope.mk:42: recipe for target '_gl_tight_scope' 
failed
make[4]: *** [_gl_tight_scope] Error 1
make[4]: Leaving directory '/home/eggert/src/gnu/grep/src'
maint.mk:1578: recipe for target 'sc_tight_scope' failed
make[3]: *** [sc_tight_scope] Error 1
make[3]: Leaving directory '/home/eggert/src/gnu/grep'
Makefile:1710: recipe for target 'run-syntax-check' failed
make[2]: *** [run-syntax-check] Error 2
make[2]: Leaving directory '/home/eggert/src/gnu/grep'
Makefile:1386: recipe for target 'distdir' failed
make[1]: *** [distdir] Error 2
make[1]: Leaving directory '/home/eggert/src/gnu/grep'
Makefile:1487: recipe for target 'dist' failed
make: *** [dist] Error 2