Revert "DIsable caching for mac"

This reverts commit a1ff9613
7 jobs for ci_mac in 66 minutes and 52 seconds
Status Job ID Name Coverage
  Test
passed #15930
Apple
Mac-Cpp11

01:06:52

passed #15929
Qt551 VS2013
VS2013-Qt-5.5.1-x64

00:16:14

passed #15928
Qt56 VS2015
VS2015-Qt-5.6.0-x32

00:19:07

passed #15927
Qt56 VS2015
VS2015-Qt-5.6.0-x64

00:21:29

passed #15925
MultiThreads Linux
clang-c++11-Qt5

00:09:00

passed #15926
MultiThreads Linux
cppcheck

00:36:40

passed #15924
Linux
gcc-c++11-Qt5

00:59:05