vppinfra: add FOREACH_ARRAY_ELT macro

Type: improvement
Change-Id: Iac1b3a66176c9a38a161246159140f30a1c168da
Signed-off-by: Damjan Marion <damarion@cisco.com>

.clang-format

@@ -20,6 +20,7 @@ ForEachMacros:
   - 'vlib_foreach_rx_tx'
   - 'foreach_vlib_main'
   - 'foreach_set_bit_index'
+  - 'FOREACH_ARRAY_ELT'
   - 'RTE_ETH_FOREACH_DEV'
 
 StatementMacros:

src/vppinfra/clib.h

@@ -74,6 +74,8 @@
 
 #define BITS(x)		(8*sizeof(x))
 #define ARRAY_LEN(x)	(sizeof (x)/sizeof (x[0]))
+#define FOREACH_ARRAY_ELT(a, b)                                               \
+  for (typeof ((b)[0]) *(a) = (b); (a) - (b) < ARRAY_LEN (b); (a)++)
 
 #define _STRUCT_FIELD(t,f) (((t *) 0)->f)
 #define STRUCT_OFFSET_OF(t,f) offsetof(t, f)