Merge branch 'dl/libify-a-few'

Code in builtin/*, i.e. those can only be called from within
built-in subcommands, that implements bulk of a couple of
subcommands have been moved to libgit.a so that they could be used
by others.

* dl/libify-a-few:
  Lib-ify prune-packed
  Lib-ify fmt-merge-msg

Makefile

@@ -880,6 +880,7 @@ LIB_OBJS += ewah/ewah_rlw.o
 LIB_OBJS += exec-cmd.o
 LIB_OBJS += fetch-negotiator.o
 LIB_OBJS += fetch-pack.o
+LIB_OBJS += fmt-merge-msg.o
 LIB_OBJS += fsck.o
 LIB_OBJS += fsmonitor.o
 LIB_OBJS += gettext.o
@@ -946,6 +947,7 @@ LIB_OBJS += progress.o
 LIB_OBJS += promisor-remote.o
 LIB_OBJS += prompt.o
 LIB_OBJS += protocol.o
+LIB_OBJS += prune-packed.o
 LIB_OBJS += quote.o
 LIB_OBJS += range-diff.o
 LIB_OBJS += reachable.o

builtin.h

@@ -94,25 +94,9 @@
  * command.
  */
 
-#define DEFAULT_MERGE_LOG_LEN 20
-
 extern const char git_usage_string[];
 extern const char git_more_info_string[];
 
-#define PRUNE_PACKED_DRY_RUN 01
-#define PRUNE_PACKED_VERBOSE 02
-
-void prune_packed_objects(int);
-
-struct fmt_merge_msg_opts {
-	unsigned add_title:1,
-		credit_people:1;
-	int shortlog_len;
-};
-
-int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
-		  struct fmt_merge_msg_opts *);
-
 /**
  * If a built-in has DELAY_PAGER_CONFIG set, the built-in should call this early
  * when it wishes to respect the `pager.foo`-config. The `cmd` is the name of