maint: prefer countof over ARRAY_CARDINALITY

* bootstrap.conf (gnulib_modules): Add stdcountof-h.
* src/system.h: Include stdcountof.h.
(ARRAY_CARDINALITY): Remove definition.
* .gitignore (/lib/stdcountof.h): Ignore Gnulib generated file.
* src/csplit.c: Use countof instead of ARRAY_CARDINALITY.
* src/df.c: Likewise.
* src/digest.c: Likewise.
* src/dircolors.c: Likewise.
* src/factor.c: Likewise.
* src/join.c: Likewise.
* src/ls.c: Likewise.
* src/od.c: Likewise.
* src/sort.c: Likewise.
* src/stdbuf.c: Likewise.
* src/tr.c: Likewise.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/df.c b/src/df.c
index 857f76cf4..75e638c5e 100644
--- a/src/df.c
+++ b/src/df.c
@@ -441,7 +441,7 @@ decode_output_arg (char const *arg)
 
       /* process S.  */
       display_field_t field = INVALID_FIELD;
-      for (idx_t i = 0; i < ARRAY_CARDINALITY (field_data); i++)
+      for (idx_t i = 0; i < countof (field_data); i++)
         {
           if (streq (field_data[i].arg, s))
             {