[Travis-CI] rollback to XCode 7.4

.travis.yml

@@ -109,7 +109,7 @@ matrix:
     # 5th parallel build job - mac osx build
     - env: "JOB=MacOSX"
       os: osx
-      osx_image: xcode10.1
+      osx_image: xcode7.3
       #cache:
       #  directories:
       #    - /usr/local/Cellar

build/travis/job_macos/before_install.sh

@@ -1,5 +1,6 @@
 #!/bin/bash
 
+cmake --version
 export QT_SHORT_VERSION=5.9
 export QT_LONG_VERSION=5.9.3
 export QT_INSTALLER_ROOT=qt-opensource-mac-x64-clang-${QT_LONG_VERSION}