Appease Sun Studio by renaming "tmpfile"

On Solaris the system headers define the "tmpfile" name, which'll
cause Git compiled with Sun Studio 12 Update 1 to whine about us
redefining the name:

    "pack-write.c", line 76: warning: name redefined by pragma redefine_extname declared static: tmpfile     (E_PRAGMA_REDEFINE_STATIC)
    "sha1_file.c", line 2455: warning: name redefined by pragma redefine_extname declared static: tmpfile    (E_PRAGMA_REDEFINE_STATIC)
    "fast-import.c", line 858: warning: name redefined by pragma redefine_extname declared static: tmpfile   (E_PRAGMA_REDEFINE_STATIC)
    "builtin/index-pack.c", line 175: warning: name redefined by pragma redefine_extname declared static: tmpfile    (E_PRAGMA_REDEFINE_STATIC)

Just renaming the "tmpfile" variable to "tmp_file" in the relevant
places is the easiest way to fix this.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/fast-import.c b/fast-import.c
index 4b9c4b7..6cd19e5 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -855,15 +855,15 @@
 
 static void start_packfile(void)
 {
-	static char tmpfile[PATH_MAX];
+	static char tmp_file[PATH_MAX];
 	struct packed_git *p;
 	struct pack_header hdr;
 	int pack_fd;
 
-	pack_fd = odb_mkstemp(tmpfile, sizeof(tmpfile),
+	pack_fd = odb_mkstemp(tmp_file, sizeof(tmp_file),
 			      "pack/tmp_pack_XXXXXX");
-	p = xcalloc(1, sizeof(*p) + strlen(tmpfile) + 2);
-	strcpy(p->pack_name, tmpfile);
+	p = xcalloc(1, sizeof(*p) + strlen(tmp_file) + 2);
+	strcpy(p->pack_name, tmp_file);
 	p->pack_fd = pack_fd;
 	p->do_not_close = 1;
 	pack_file = sha1fd(pack_fd, p->pack_name);