[build] Avoid implicit-fallthrough warnings on GCC 7

Reported-by: Vinson Lee <vlee@freedesktop.org>
Reported-by: Liang Yan <lyan@suse.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/x86/image/bzimage.c

 		case 'G':
 		case 'g':
 			bzimg->mem_limit <<= 10;
+			/* Fall through */
 		case 'M':
 		case 'm':
 			bzimg->mem_limit <<= 10;
+			/* Fall through */
 		case 'K':
 		case 'k':
 			bzimg->mem_limit <<= 10;

src/drivers/infiniband/golan.c

 	case GOLAN_PORT_CHANGE_SUBTYPE_CLIENT_REREG:
 	case GOLAN_PORT_CHANGE_SUBTYPE_ACTIVE:
 		golan_ib_update ( ibdev );
+		/* Fall through */
 	case GOLAN_PORT_CHANGE_SUBTYPE_DOWN:
 	case GOLAN_PORT_CHANGE_SUBTYPE_LID:
 	case GOLAN_PORT_CHANGE_SUBTYPE_PKEY:

src/drivers/net/ath/ath9k/ath9k_ar5008_phy.c

 	case 0x5:
 		REG_SET_BIT(ah, AR_PHY_ANALOG_SWAP,
 			    AR_PHY_SWAP_ALT_CHAIN);
+		/* Fall through */
 	case 0x3:
 		if (ah->hw_version.macVersion == AR_SREV_REVISION_5416_10) {
 			REG_WRITE(ah, AR_PHY_RX_CHAINMASK, 0x7);
 			REG_WRITE(ah, AR_PHY_CAL_CHAINMASK, 0x7);
 			break;
 		}
+		/* Fall through */
 	case 0x1:
 	case 0x2:
 	case 0x7:

src/drivers/net/ath/ath9k/ath9k_ar9002_phy.c

 				aModeRefSel = 2;
 			if (aModeRefSel)
 				break;
+			/* Fall through */
 		case 1:
 		default:
 			aModeRefSel = 0;

src/drivers/net/ath/ath9k/ath9k_ar9003_phy.c

 	case 0x5:
 		REG_SET_BIT(ah, AR_PHY_ANALOG_SWAP,
 			    AR_PHY_SWAP_ALT_CHAIN);
+		/* Fall through */
 	case 0x3:
 	case 0x1:
 	case 0x2:

src/drivers/net/igbvf/igbvf_vf.c

 		break;
 	case e1000_promisc_enabled:
 		msgbuf |= E1000_VF_SET_PROMISC_MULTICAST;
+		/* Fall through */
 	case e1000_promisc_unicast:
 		msgbuf |= E1000_VF_SET_PROMISC_UNICAST;
 	case e1000_promisc_disabled:

src/drivers/net/tg3/tg3_hw.c

 	switch (limit) {
 	case 16:
 		tw32(MAC_RCV_RULE_15,  0); tw32(MAC_RCV_VALUE_15,  0);
+		/* Fall through */
 	case 15:
 		tw32(MAC_RCV_RULE_14,  0); tw32(MAC_RCV_VALUE_14,  0);
+		/* Fall through */
 	case 14:
 		tw32(MAC_RCV_RULE_13,  0); tw32(MAC_RCV_VALUE_13,  0);
+		/* Fall through */
 	case 13:
 		tw32(MAC_RCV_RULE_12,  0); tw32(MAC_RCV_VALUE_12,  0);
+		/* Fall through */
 	case 12:
 		tw32(MAC_RCV_RULE_11,  0); tw32(MAC_RCV_VALUE_11,  0);
+		/* Fall through */
 	case 11:
 		tw32(MAC_RCV_RULE_10,  0); tw32(MAC_RCV_VALUE_10,  0);
+		/* Fall through */
 	case 10:
 		tw32(MAC_RCV_RULE_9,  0); tw32(MAC_RCV_VALUE_9,  0);
+		/* Fall through */
 	case 9:
 		tw32(MAC_RCV_RULE_8,  0); tw32(MAC_RCV_VALUE_8,  0);
+		/* Fall through */
 	case 8:
 		tw32(MAC_RCV_RULE_7,  0); tw32(MAC_RCV_VALUE_7,  0);
+		/* Fall through */
 	case 7:
 		tw32(MAC_RCV_RULE_6,  0); tw32(MAC_RCV_VALUE_6,  0);
+		/* Fall through */
 	case 6:
 		tw32(MAC_RCV_RULE_5,  0); tw32(MAC_RCV_VALUE_5,  0);
+		/* Fall through */
 	case 5:
 		tw32(MAC_RCV_RULE_4,  0); tw32(MAC_RCV_VALUE_4,  0);
+		/* Fall through */
 	case 4:
 		/* tw32(MAC_RCV_RULE_3,  0); tw32(MAC_RCV_VALUE_3,  0); */
 	case 3:

src/tests/setjmp_test.c

  * @v file		Test code file
  * @v line		Test code line
  */
-static void longjmp_okx ( struct setjmp_test *test, int value,
-			  const char *file, unsigned int line ) {
+static void __attribute__ (( noreturn ))
+longjmp_okx ( struct setjmp_test *test, int value,
+	      const char *file, unsigned int line ) {
 
 	/* Record expected value.  A zero passed to longjmp() should
 	 * result in setjmp() returning a value of one.