.travis.yml: Add a KVM-only Aarch64 job

Add a job to build QEMU on Aarch64 with TCG disabled, so
this configuration won't bitrot over time.

We explicitly modify default-configs/aarch64-softmmu.mak to
only select the 'virt' and 'SBSA-REF' machines.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
Job ran for 7 min 30 sec
https://travis-ci.org/github/philmd/qemu/jobs/731428859
73 jobs for kvm_arm6 in 59 minutes and 23 seconds (queued for 2 seconds)
latest
Status Name Job ID Coverage
  Build
passed build-clang #997660859

00:42:57

passed build-coroutine-sigaltstack #997660865

00:15:58

passed build-coroutine-ucontext #997660864

00:16:22

passed build-crypto-old-gcrypt #997660867

00:12:04

passed build-crypto-old-nettle #997660866

00:11:54

passed build-crypto-only-gnutls #997660868

00:11:47

passed build-deprecated #997660860

00:12:53

passed build-disabled #997660851

00:29:38

passed build-libvhost-user #997660876

00:03:18

passed build-oss-fuzz #997660862

00:43:25

passed build-some-softmmu #997660855

00:22:26

passed build-some-softmmu-plugins #997660858

00:23:27

passed build-system-alpine #997660844

00:38:21

passed build-system-centos #997660849

00:21:04

passed build-system-debian #997660846

00:28:58

passed build-system-fedora #997660848

00:27:33

passed build-system-opensuse #997660850

00:19:41

passed build-system-ubuntu #997660845

00:27:04

passed build-tcg-disabled #997660852

00:21:07

passed build-tci #997660863

00:33:37

passed build-tools-and-docs-debian #997660847

00:08:56

passed build-trace-ftrace-system #997660870

00:14:53

passed build-trace-multi-user #997660869

00:42:00

passed build-trace-ust-system #997660871

00:21:11

passed build-user #997660853

00:43:46

passed build-user-centos7 #997660857

00:30:22

passed build-user-plugins #997660856

00:40:20

passed build-user-static #997660854

00:39:30

passed build-without-default-devices #997660872

00:44:07

passed build-without-default-features #997660873

00:44:26

passed check-dco #997660875

00:01:03

passed check-patch #997660874

00:01:06

passed cross-amd64-xen-only #997660842

00:14:06

passed cross-arm64-system #997660825

00:52:31

passed cross-arm64-user #997660826

00:43:40

passed cross-arm64-xen-only #997660843

00:16:46

passed cross-armel-system #997660821

00:56:34

passed cross-armel-user #997660822

00:46:17

passed cross-armhf-system #997660823

00:48:50

passed cross-armhf-user #997660824

00:45:29

passed cross-i386-system #997660827

00:57:22

passed cross-i386-user #997660828

00:41:42

passed cross-mips-system #997660829

00:53:10

passed cross-mips-user #997660830

00:46:05

passed cross-mips64el-system #997660833

00:52:58

passed cross-mips64el-user #997660834

00:44:00

passed cross-mipsel-system #997660831

00:53:55

passed cross-mipsel-user #997660832

00:45:34

passed cross-ppc64el-system #997660835

00:49:03

passed cross-ppc64el-user #997660836

00:44:43

passed cross-s390x-kvm-only #997660839

00:11:00

passed cross-s390x-system #997660837

00:46:14

passed cross-s390x-user #997660838

00:42:29

passed cross-win32-system #997660840

00:52:38

passed cross-win64-system #997660841

00:59:19

 
  Test
passed acceptance-system-alpine #997660878

00:03:47

passed acceptance-system-centos #997660886

00:04:34

passed acceptance-system-debian #997660882

00:07:58

passed acceptance-system-fedora #997660884

00:08:31

passed acceptance-system-opensuse #997660888

00:04:11

passed acceptance-system-ubuntu #997660880

00:05:29

passed check-crypto-old-gcrypt #997660891

00:09:02

passed check-crypto-old-nettle #997660890

00:08:41

passed check-crypto-only-gnutls #997660892

00:08:56

passed check-deprecated #997660889

00:03:28

passed check-system-alpine #997660877

00:08:19

passed check-system-centos #997660885

00:10:54

passed check-system-debian #997660881

00:17:52

passed check-system-fedora #997660883

00:10:19

passed check-system-opensuse #997660887

00:14:30

passed check-system-ubuntu #997660879

00:13:39

passed pages #997660893

00:09:21

 
  Deploy
passed pages:deploy

00:10:45