build error with icc version 17.0.4 (gcc version 7.0.0 compatibility):
In file included from .../dpdk/lib/librte_hash/rte_fbk_hash.h(59),
                 from .../dpdk/lib/librte_hash/rte_fbk_hash.c(54):
.../dpdk/x86_64-native-linuxapp-icc/include/rte_hash_crc.h(480):
 error #1292: unknown attribute "fallthrough"
                __attribute__ ((fallthrough));
                                ^
In file included from .../dpdk/lib/librte_hash/rte_fbk_hash.h(59),
                 from .../dpdk/lib/librte_hash/rte_fbk_hash.c(54):
.../dpdk/x86_64-native-linuxapp-icc/include/rte_hash_crc.h(486):
 error #1292: unknown attribute "fallthrough"
                __attribute__ ((fallthrough));
                                ^
This code patch hit when gcc > 7 installed and ICC doesn't recognize
fallthrough attribute.
Fixed by disabling code when compiled with ICC.
Fixes: 3dfb9facb055 ("lib: add switch fall-through comments")
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
        case CRC32_SSE42_x64:
                if (! rte_cpu_get_flag_enabled(RTE_CPUFLAG_EM64T))
                        alg = CRC32_SSE42;
-#if __GNUC__ >= 7
+#if __GNUC__ >= 7 && !defined(RTE_TOOLCHAIN_ICC)
                __attribute__ ((fallthrough));
 #endif
        case CRC32_SSE42:
                if (! rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_2))
                        alg = CRC32_SW;
-#if __GNUC__ >= 7
+#if __GNUC__ >= 7 && !defined(RTE_TOOLCHAIN_ICC)
                __attribute__ ((fallthrough));
 #endif
 #endif