042dfb3ec5
* 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: I659aa617dad0ed7eb23967215c37586ef168d88c