git.c: remove unnecessary #includes

"cache.h" and "commit.h" are already included via "builtin.h".

We started to include "quote.h" at 575ba9d (GIT_TRACE: show which
built-in/external commands are executed, 2006-06-25) that wanted to
use sq_quote_print().

When 6ce4e61 (Trace into a file or an open fd and refactor tracing
code., 2006-09-02) introduced trace.c API, the calls this file makes
to sq_quote_print() were replaced by calls to trace_argv_printf()
that are declared in "cache.h", which this file already includes.
We should have stopped including "quote.h" in that commit, but
forgot to do so.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git.c

@@ -1,10 +1,7 @@
 #include "builtin.h"
-#include "cache.h"
 #include "exec_cmd.h"
 #include "help.h"
-#include "quote.h"
 #include "run-command.h"
-#include "commit.h"
 
 const char git_usage_string[] =
 	"git [--version] [--help] [-C <path>] [-c name=value]\n"