util: move all to shared/ and split external dependencies in separate internal libraries

Before:
  $ ldd /lib/systemd/systemd-timestamp
  linux-vdso.so.1 =>  (0x00007fffb05ff000)
  libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f90aac57000)
  libcap.so.2 => /lib64/libcap.so.2 (0x00007f90aaa53000)
  librt.so.1 => /lib64/librt.so.1 (0x00007f90aa84a000)
  libc.so.6 => /lib64/libc.so.6 (0x00007f90aa494000)
  /lib64/ld-linux-x86-64.so.2 (0x00007f90aae90000)
  libdl.so.2 => /lib64/libdl.so.2 (0x00007f90aa290000)
  libattr.so.1 => /lib64/libattr.so.1 (0x00007f90aa08a000)
  libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f90a9e6e000)

After:
  $ ldd systemd-timestamp
  linux-vdso.so.1 =>  (0x00007fff3cbff000)
  libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f5eaa1c3000)
  librt.so.1 => /lib64/librt.so.1 (0x00007f5ea9fbb000)
  libc.so.6 => /lib64/libc.so.6 (0x00007f5ea9c04000)
  /lib64/ld-linux-x86-64.so.2 (0x00007f5eaa3fc000)
  libdl.so.2 => /lib64/libdl.so.2 (0x00007f5ea9a00000)
  libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f5ea97e4000)

1 files changed, 91 insertions, 0 deletions

diff --git a/src/shared/hashmap.h b/src/shared/hashmap.h
new file mode 100644
index 0000000000..ab4363a7a3
--- /dev/null
+++ b/src/shared/hashmap.h
@@ -0,0 +1,91 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef foohashmaphfoo
+#define foohashmaphfoo
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdbool.h>
+
+/* Pretty straightforward hash table implementation. As a minor
+ * optimization a NULL hashmap object will be treated as empty hashmap
+ * for all read operations. That way it is not necessary to
+ * instantiate an object for each Hashmap use. */
+
+typedef struct Hashmap Hashmap;
+typedef struct _IteratorStruct _IteratorStruct;
+typedef _IteratorStruct* Iterator;
+
+#define ITERATOR_FIRST ((Iterator) 0)
+#define ITERATOR_LAST ((Iterator) -1)
+
+typedef unsigned (*hash_func_t)(const void *p);
+typedef int (*compare_func_t)(const void *a, const void *b);
+
+unsigned string_hash_func(const void *p);
+int string_compare_func(const void *a, const void *b);
+
+unsigned trivial_hash_func(const void *p);
+int trivial_compare_func(const void *a, const void *b);
+
+Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func);
+void hashmap_free(Hashmap *h);
+void hashmap_free_free(Hashmap *h);
+Hashmap *hashmap_copy(Hashmap *h);
+int hashmap_ensure_allocated(Hashmap **h, hash_func_t hash_func, compare_func_t compare_func);
+
+int hashmap_put(Hashmap *h, const void *key, void *value);
+int hashmap_replace(Hashmap *h, const void *key, void *value);
+void* hashmap_get(Hashmap *h, const void *key);
+void* hashmap_remove(Hashmap *h, const void *key);
+void* hashmap_remove_value(Hashmap *h, const void *key, void *value);
+int hashmap_remove_and_put(Hashmap *h, const void *old_key, const void *new_key, void *value);
+int hashmap_remove_and_replace(Hashmap *h, const void *old_key, const void *new_key, void *value);
+
+int hashmap_merge(Hashmap *h, Hashmap *other);
+void hashmap_move(Hashmap *h, Hashmap *other);
+int hashmap_move_one(Hashmap *h, Hashmap *other, const void *key);
+
+unsigned hashmap_size(Hashmap *h);
+bool hashmap_isempty(Hashmap *h);
+
+void *hashmap_iterate(Hashmap *h, Iterator *i, const void **key);
+void *hashmap_iterate_backwards(Hashmap *h, Iterator *i, const void **key);
+void *hashmap_iterate_skip(Hashmap *h, const void *key, Iterator *i);
+
+void hashmap_clear(Hashmap *h);
+void *hashmap_steal_first(Hashmap *h);
+void *hashmap_steal_first_key(Hashmap *h);
+void* hashmap_first(Hashmap *h);
+void* hashmap_first_key(Hashmap *h);
+void* hashmap_last(Hashmap *h);
+
+char **hashmap_get_strv(Hashmap *h);
+
+#define HASHMAP_FOREACH(e, h, i) \
+        for ((i) = ITERATOR_FIRST, (e) = hashmap_iterate((h), &(i), NULL); (e); (e) = hashmap_iterate((h), &(i), NULL))
+
+#define HASHMAP_FOREACH_KEY(e, k, h, i) \
+        for ((i) = ITERATOR_FIRST, (e) = hashmap_iterate((h), &(i), (const void**) &(k)); (e); (e) = hashmap_iterate((h), &(i), (const void**) &(k)))
+
+#define HASHMAP_FOREACH_BACKWARDS(e, h, i) \
+        for ((i) = ITERATOR_LAST, (e) = hashmap_iterate_backwards((h), &(i), NULL); (e); (e) = hashmap_iterate_backwards((h), &(i), NULL))
+
+#endif