daemon: Use inline functions and variables instead of extern

Avoid separate declarations and definitions for so-called 'global' objects.

* nix/libstore/derivations.{cc, hh} (drvHashes): Use inline instead of separate
declaration and definition.
* nix/libstore/globals.{cc, hh} (settings, nixVersion): Same.
* nix/libstore/local-store.hh (drvsLogDir, deduplicationMinSize): Same.
* nix/libstore/optimise-store.cc (deduplicationMinSize): Same.
* nix/libstore/store-api.{cc, hh} (store): Same.
* nix/libutil/archive.{cc, hh} (defaultPathFilter): Same.
* nix/libutil/hash.{cc, hh} (base32Chars): Same and modify header files.
* nix/libutil/util.{cc, hh} (logType, verbosity, _writeToStderr,
_isInterrupted): Same.
* nix/local.mk: Modified according to the rename of shared.hh.
* nix/nix-daemon/guix-daemon.cc (blockInt, argvSaved, run): Same and
modify header files.
* nix/nix-daemon/nix-daemon.cc: Modify header files.
* nix/nix-daemon/shared.hh: Renamed to nix-daemon.hh

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

nix/libstore/optimise-store.cc

@@ -16,9 +16,6 @@
 
 namespace nix {
 
-/* Any file smaller than this is not considered for deduplication.
-   Keep in sync with (guix store deduplication).  */
-const size_t deduplicationMinSize = 8192;
 
 static void makeWritable(const Path & path)
 {