Enable -fvisibility=hidden for src/misc/.

* configure.ac: Check for -fvisibility support.
* m4/ax_check_compile_flag.m4: New file.
* src/misc/common.hh: New file.
* src/misc/Makefile.am: Add common.hh, and adjust to use -fvisibility.
* src/misc/bareword.hh, src/misc/escape.hh, src/misc/formater.hh,
src/misc/intvcmp2.hh, src/misc/intvcomp.hh, src/misc/memusage.hh,
src/misc/minato.hh, src/misc/optionmap.hh, src/misc/random.hh,
src/misc/timer.hh, src/misc/version.hh, src/misc/bddop.hh: Include
common.hh and add SPOT_API tags.
* src/misc/acccompl.hh, src/misc/accconv.hh: Prepare for upcoming
move.
* src/sanity/style.test: Ignore SPOT_API tags.
* wrap/python/Makefile.am: Ignore SPOT_API.
* wrap/python/spot.i: Do not emit binding for bddalloc.hh.
* wrap/python/tests/minato.py: Do not use bdd_allocator.

src/sanity/style.test

@@ -86,10 +86,13 @@ for dir in "${INCDIR-..}" "${INCDIR-..}"/../iface; do
     # //
     # //
     # to keep the line numbers correct in the diagnostics.
+    #
+    # Also get read of the SPOT_API tags.
     perl -pe 'sub f {my $a = shift; $a =~ s:[^\n]*://:g; return "$a"}
               s,/\*(.*?)\*/,f($1),sge;
               s,//.*?\n,//\n,g;
-              s,"[^"\n]*","",g' -0777 <$file >$tmp
+              s,"[^"\n]*","",g;
+              s,SPOT_API ,,g' -0777 <$file >$tmp
 
     grep '[	 ]$' $tmp &&
       diag 'Trailing whitespace.'