user_ident_sufficiently_given(): refactor the logic to be usable from elsewhere

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-commit.c

@@ -624,7 +624,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 				author_ident);
 		free(author_ident);
 
-		if (user_ident_explicitly_given != IDENT_ALL_GIVEN)
+		if (!user_ident_sufficiently_given())
 			fprintf(fp,
 				"%s"
 				"# Committer: %s\n",

cache.h

@@ -929,6 +929,7 @@ extern char git_default_name[MAX_GITNAME];
 #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;
 extern const char *git_log_output_encoding;

ident.c

@@ -259,3 +259,12 @@ const char *git_committer_info(int flag)
 			 getenv("GIT_COMMITTER_DATE"),
 			 flag);
 }
+
+int user_ident_sufficiently_given(void)
+{
+#ifndef WINDOWS
+	return (user_ident_explicitly_given & IDENT_MAIL_GIVEN);
+#else
+	return (user_ident_explicitly_given == IDENT_ALL_GIVEN);
+#endif
+}