uniqstr: fix assertion

* src/uniqstr.c (uniqstr_assert): Really make sure str is a uniqstr,
not just whether some uniqstr with the same content was registered.
tests: minor change to make it easier to test other skeletons

* tests/c++.at (Variants): Pass the skeleton as argument.
build: port to pre-5.8.7 perl

* examples/local.mk (extract): Omit -f from perl options.
This doesn't work with perl versions before 5.8.7
that are configured without USE_SITECUSTOMIZE.
Reported by Michael Felt in
<http://lists.gnu.org/archive/html/bug-bison/2013-08/msg00006.html>.
maint: update .gitignore

* .gitignore: Add *.eps, *.o, *.pdf, *.png, *.stamp, *~,
.deps, .dirstamp.  Needed to suppress unwanted chatter from
'git status' after a bootstrap build.
build: don't require flex for ordinary builds

* configure.ac (LEX): Don't fail if this is lex, as flex is not
required for ordinary builds.  Instead, issue a warning and
substitute a no-op LEX.  Reported by Michael Felt in
<http://lists.gnu.org/archive/html/bug-bison/2013-08/msg00009.html>.
tests: do not use grep -q

Reported by Daniel Galloway.
http://lists.gnu.org/archive/html/bug-bison/2013-08/msg00020.html

* tests/java.at: Ignore grep's output instead.
tests: remove stray debugging traces

* tests/atlocal.in: Remove traces.
Be ready to remove conftest.dSYM generated on OS X.
variant: remove useless assertion

* data/variant.hh (move): Remove precondition assertion which is
ensured by the first call of the body (this precondition is also one
of "build").
examples: improve the output of the "variant" example

* examples/variant.yy: Improve the printing of lists.
glr: better use of tracing macros

* data/glr.c (yydestroyGLRState): Use YY_SYMBOL_PRINT instead of
yy_symbol_print.
glr: formatting changes

* data/glr.c: here.
glr: shorten scopes

* data/glr.c (yyglrReduce): Define yyflag with its value.
glr: more assertions

* data/glr.c (yyaddDeferredAction, yyglrShiftDefer, yypdumpstack):
More assertions.
glr: simplify the invocation of YYLLOC_DEFAULT

The commit which introduces yyresolveLocations (commit
8710fc41aaebc5d167a2783a4b8b60849a803869) saves and restores the
look-ahead (type, value and location) for no clear reason.  This
appears to be useless.

* data/glr.c (yyresolveLocations): Don't save/restore the current
look-ahead to call YYLLOC_DEFAULT.
Minor style changes.
Merge remote-tracking branch 'origin/maint'

* origin/maint:
  glr: more assertions
  glr: shorten scopes
  glr: formatting changes
  glr: better use of tracing macros
  examples: improve the output of the "variant" example
  variant: remove useless assertion
  tests: remove stray debugging traces
  tests: do not use grep -q
  build: don't require flex for ordinary builds
  maint: update .gitignore
  build: port to pre-5.8.7 perl
  tests: minor change to make it easier to test other skeletons
  uniqstr: fix assertion