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, 79 insertions, 0 deletions

diff --git a/src/shared/strv.h b/src/shared/strv.h
new file mode 100644
index 0000000000..d038c9f3b1
--- /dev/null
+++ b/src/shared/strv.h
@@ -0,0 +1,79 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef foostrvhfoo
+#define foostrvhfoo
+
+/***
+  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 <stdarg.h>
+#include <stdbool.h>
+
+#include "macro.h"
+
+char *strv_find(char **l, const char *name);
+char *strv_find_prefix(char **l, const char *name);
+
+void strv_free(char **l);
+char **strv_copy(char **l) _malloc_;
+unsigned strv_length(char **l);
+
+char **strv_merge(char **a, char **b);
+char **strv_merge_concat(char **a, char **b, const char *suffix);
+char **strv_append(char **l, const char *s);
+
+char **strv_remove(char **l, const char *s);
+char **strv_uniq(char **l);
+
+#define strv_contains(l, s) (!!strv_find((l), (s)))
+
+char **strv_new(const char *x, ...) _sentinel_ _malloc_;
+char **strv_new_ap(const char *x, va_list ap) _malloc_;
+
+static inline bool strv_isempty(char **l) {
+        return !l || !*l;
+}
+
+char **strv_split(const char *s, const char *separator) _malloc_;
+char **strv_split_quoted(const char *s) _malloc_;
+
+char *strv_join(char **l, const char *separator) _malloc_;
+
+char **strv_env_merge(unsigned n_lists, ...);
+char **strv_env_delete(char **x, unsigned n_lists, ...);
+
+char **strv_env_set(char **x, const char *p);
+char **strv_env_unset(char **l, const char *p);
+
+char *strv_env_get_with_length(char **l, const char *name, size_t k);
+char *strv_env_get(char **x, const char *n);
+
+char **strv_env_clean(char **l);
+
+char **strv_parse_nulstr(const char *s, size_t l);
+
+bool strv_overlap(char **a, char **b);
+
+#define STRV_FOREACH(s, l)                      \
+        for ((s) = (l); (s) && *(s); (s)++)
+
+#define STRV_FOREACH_BACKWARDS(s, l)            \
+        for (; (l) && ((s) >= (l)); (s)--)
+
+#endif