Optimize: Use a hash table in compute_partition.

This reduces the execution time of gperf on large inputs by ca. 30%.

* autogen.sh (GNULIB_MODULES): Add map-c++, hash-map.
* src/keyword.h: Include <stddef.h>.
(struct KeywordExt): Add fields _undetermined_chars,
_undetermined_chars_length, _undetermined_chars_hashcode.
* src/search.cc: Include gl_map.hh, gl_hash_map.h.
(Search::prepare_asso_values): Initialize the _undetermined_chars field.
(struct EquivalenceClass): Remove the fields _undetermined_chars,
_undetermined_chars_length.
(undetermined_equals, undetermined_hashcode): New functions.
(Search::compute_partition): Initialize the _undetermined_chars* fields
of all keywords. Use a hash map instead of a loop over the equivalence
classes.
(Search::find_good_asso_values): Deallocate the _undetermined_chars field.

lib/.gitignore

@@ -5,12 +5,19 @@
 /alloca.in.h
 /arg-nonnull.h
 /assert.in.h
+/attribute.h
+/basename-lgpl.c
+/basename-lgpl.h
 /c++defs.h
 /cloexec.c
 /cloexec.h
 /close.c
 /dup2.c
 /errno.in.h
+/error.c
+/error.in.h
+/exitfail.c
+/exitfail.h
 /fcntl.c
 /fcntl.in.h
 /fd-hook.c
@@ -31,9 +38,22 @@
 /getopt.in.h
 /getopt1.c
 /getopt_int.h
+/getprogname.c
+/getprogname.h
 /gettext.h
+/gl_anyhash1.h
+/gl_anyhash2.h
+/gl_anyhash_primes.h
+/gl_hash_map.c
+/gl_hash_map.h
+/gl_map.c
+/gl_map.h
+/gl_map.hh
+/gl_xmap.c
+/gl_xmap.h
 /idx.h
 /intprops-internal.h
+/intprops.h
 /inttypes.in.h
 /limits.in.h
 /lseek.c
@@ -51,6 +71,7 @@
 /read-file.c
 /read-file.h
 /realloc.c
+/size_max.h
 /stat-time.c
 /stat-time.h
 /stat-w32.c
@@ -65,6 +86,9 @@
 /stdio.in.h
 /stdlib.c
 /stdlib.in.h
+/strerror-override.c
+/strerror-override.h
+/strerror.c
 /string.in.h
 /sys_stat.in.h
 /sys_types.in.h
@@ -74,7 +98,11 @@
 /verify.h
 /warn-on-use.h
 /wchar.in.h
+/xalloc-die.c
 /xalloc-oversized.h
+/xalloc.h
+/xsize.c
+/xsize.h
 
 # Files generated by the autotools:
 /aclocal.m4