pager: config variable pager.color

enable/disable colored output when the pager is in use

Signed-off-by: Matthias Lederhofer <matled@gmx.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

environment.c

@@ -23,6 +23,7 @@ int shared_repository = PERM_UMASK;
 const char *apply_default_whitespace = NULL;
 int zlib_compression_level = Z_DEFAULT_COMPRESSION;
 int pager_in_use;
+int pager_use_color = 1;
 
 static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir,
 	*git_graft_file;