README, travis.yml: rm ambient tag

This build tag was removed in commit 4f903a21c4 (PR #1370)
quite some time ago.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

.travis.yml

@@ -43,7 +43,7 @@ services:
 
 env:
   global:
-    - BUILDTAGS="seccomp apparmor selinux ambient"
+    - BUILDTAGS="seccomp apparmor selinux"
 
 before_install:
   - sudo apt-get -qq update

README.md

@@ -72,7 +72,6 @@ make BUILDTAGS='seccomp apparmor'
 | seccomp   | Syscall filtering                  | libseccomp  |
 | selinux   | selinux process and mount labeling | <none>      |
 | apparmor  | apparmor profile support           | <none>      |
-| ambient   | ambient capability support         | kernel 4.3  |
 | nokmem    | disable kernel memory account      | <none>      |