build: align minimum build dependencies with ndn-cxx
* Recommend gcc >= 7.4.0
* Require clang >= 4.0, or Xcode >= 9.0 on macOS
* Silence an ABI-related diagnostic message from gcc on armv7
* Update Travis CI job matrix
Refs: #5087, #5106
Change-Id: I71aef00147a7ad93b537904bb309745fed77f509
diff --git a/.travis.yml b/.travis.yml
index 54ce733..2e7caab 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -38,6 +38,12 @@
- os: osx
osx_image: xcode11.3
env: # default compiler
+ - os: osx
+ osx_image: xcode11.6
+ env: # default compiler
+ - os: osx
+ osx_image: xcode12
+ env: # default compiler
allow_failures:
- arch: s390x # bug 5098