ident: make user_ident_explicitly_given static

In v1.5.6-rc0~56^2 (2008-05-04) "user_ident_explicitly_given"
was introduced as a global for communication between config,
ident, and builtin-commit.  In v1.7.0-rc0~72^2 (2010-01-07)
readers switched to using the common wrapper
user_ident_sufficiently_given().  After v1.7.11-rc1~15^2~18
(2012-05-21), the var is only written in ident.c.

Now we can make it static, which will enable further
refactoring without worrying about upsetting other code.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -1149,10 +1149,6 @@ struct config_include_data {
 #define CONFIG_INCLUDE_INIT { 0 }
 extern int git_config_include(const char *name, const char *value, void *data);
 
-#define IDENT_NAME_GIVEN 01
-#define IDENT_MAIL_GIVEN 02
-#define IDENT_ALL_GIVEN (IDENT_NAME_GIVEN|IDENT_MAIL_GIVEN)
-extern int user_ident_explicitly_given;
 extern int user_ident_sufficiently_given(void);
 
 extern const char *git_commit_encoding;

ident.c

@@ -10,7 +10,11 @@
 static struct strbuf git_default_name = STRBUF_INIT;
 static struct strbuf git_default_email = STRBUF_INIT;
 static char git_default_date[50];
-int user_ident_explicitly_given;
+
+#define IDENT_NAME_GIVEN 01
+#define IDENT_MAIL_GIVEN 02
+#define IDENT_ALL_GIVEN (IDENT_NAME_GIVEN|IDENT_MAIL_GIVEN)
+static int user_ident_explicitly_given;
 
 #ifdef NO_GECOS_IN_PWENT
 #define get_gecos(ignored) "&"