Replace filepattern with pathspec for consistency

pathspec is the most widely used term, and is the one defined in
gitglossary.txt. <filepattern> was used only in the synopsys for git-add
and git-commit, and in git-add.txt. Get rid of it.

This patch is obtained with by running:

  perl -pi -e 's/filepattern/pathspec/' `git grep -l filepattern`

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/add.c

@@ -16,7 +16,7 @@
 #include "bulk-checkin.h"
 
 static const char * const builtin_add_usage[] = {
-	N_("git add [options] [--] <filepattern>..."),
+	N_("git add [options] [--] <pathspec>..."),
 	NULL
 };
 static int patch_interactive, add_interactive, edit_interactive;