Move 'builtin-*' into a 'builtin/' subdirectory

This shrinks the top-level directory a bit, and makes it much more
pleasant to use auto-completion on the thing. Instead of

	[torvalds@nehalem git]$ em buil<tab>
	Display all 180 possibilities? (y or n)
	[torvalds@nehalem git]$ em builtin-sh
	builtin-shortlog.c     builtin-show-branch.c  builtin-show-ref.c
	builtin-shortlog.o     builtin-show-branch.o  builtin-show-ref.o
	[torvalds@nehalem git]$ em builtin-shor<tab>
	builtin-shortlog.c  builtin-shortlog.o
	[torvalds@nehalem git]$ em builtin-shortlog.c

you get

	[torvalds@nehalem git]$ em buil<tab>		[type]
	builtin/   builtin.h
	[torvalds@nehalem git]$ em builtin		[auto-completes to]
	[torvalds@nehalem git]$ em builtin/sh<tab>	[type]
	shortlog.c     shortlog.o     show-branch.c  show-branch.o  show-ref.c     show-ref.o
	[torvalds@nehalem git]$ em builtin/sho		[auto-completes to]
	[torvalds@nehalem git]$ em builtin/shor<tab>	[type]
	shortlog.c  shortlog.o
	[torvalds@nehalem git]$ em builtin/shortlog.c

which doesn't seem all that different, but not having that annoying
break in "Display all 180 possibilities?" is quite a relief.

NOTE! If you do this in a clean tree (no object files etc), or using an
editor that has auto-completion rules that ignores '*.o' files, you
won't see that annoying 'Display all 180 possibilities?' message - it
will just show the choices instead.  I think bash has some cut-off
around 100 choices or something.

So the reason I see this is that I'm using an odd editory, and thus
don't have the rules to cut down on auto-completion.  But you can
simulate that by using 'ls' instead, or something similar.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/merge-index.c

@@ -0,0 +1,111 @@
+#include "cache.h"
+#include "run-command.h"
+#include "exec_cmd.h"
+
+static const char *pgm;
+static int one_shot, quiet;
+static int err;
+
+static int merge_entry(int pos, const char *path)
+{
+	int found;
+	const char *arguments[] = { pgm, "", "", "", path, "", "", "", NULL };
+	char hexbuf[4][60];
+	char ownbuf[4][60];
+
+	if (pos >= active_nr)
+		die("git merge-index: %s not in the cache", path);
+	found = 0;
+	do {
+		struct cache_entry *ce = active_cache[pos];
+		int stage = ce_stage(ce);
+
+		if (strcmp(ce->name, path))
+			break;
+		found++;
+		strcpy(hexbuf[stage], sha1_to_hex(ce->sha1));
+		sprintf(ownbuf[stage], "%o", ce->ce_mode);
+		arguments[stage] = hexbuf[stage];
+		arguments[stage + 4] = ownbuf[stage];
+	} while (++pos < active_nr);
+	if (!found)
+		die("git merge-index: %s not in the cache", path);
+
+	if (run_command_v_opt(arguments, 0)) {
+		if (one_shot)
+			err++;
+		else {
+			if (!quiet)
+				die("merge program failed");
+			exit(1);
+		}
+	}
+	return found;
+}
+
+static void merge_file(const char *path)
+{
+	int pos = cache_name_pos(path, strlen(path));
+
+	/*
+	 * If it already exists in the cache as stage0, it's
+	 * already merged and there is nothing to do.
+	 */
+	if (pos < 0)
+		merge_entry(-pos-1, path);
+}
+
+static void merge_all(void)
+{
+	int i;
+	for (i = 0; i < active_nr; i++) {
+		struct cache_entry *ce = active_cache[i];
+		if (!ce_stage(ce))
+			continue;
+		i += merge_entry(i, ce->name)-1;
+	}
+}
+
+int cmd_merge_index(int argc, const char **argv, const char *prefix)
+{
+	int i, force_file = 0;
+
+	/* Without this we cannot rely on waitpid() to tell
+	 * what happened to our children.
+	 */
+	signal(SIGCHLD, SIG_DFL);
+
+	if (argc < 3)
+		usage("git merge-index [-o] [-q] <merge-program> (-a | [--] <filename>*)");
+
+	read_cache();
+
+	i = 1;
+	if (!strcmp(argv[i], "-o")) {
+		one_shot = 1;
+		i++;
+	}
+	if (!strcmp(argv[i], "-q")) {
+		quiet = 1;
+		i++;
+	}
+	pgm = argv[i++];
+	for (; i < argc; i++) {
+		const char *arg = argv[i];
+		if (!force_file && *arg == '-') {
+			if (!strcmp(arg, "--")) {
+				force_file = 1;
+				continue;
+			}
+			if (!strcmp(arg, "-a")) {
+				merge_all();
+				continue;
+			}
+			die("git merge-index: unknown option %s", arg);
+		}
+		merge_file(arg);
+	}
+	if (err && !quiet)
+		die("merge program failed");
+	return err;
+}