Provisioning: Install Devtoolset-4 to Rhel 7.4

Gcc need to be downgraded from 6 to 5, because Gcc 6 is too new for
the latest Ubuntu LTS (16.04). This means Devtoolset-4 need to be used
instead of Devtoolset-6.

Task-number: QTBUG-64820
Change-Id: I2601aaaff5f3bbbadd867105fd4155239ab89825
Reviewed-by: Konstantin Tokarev <annulen@yandex.ru>

coin/provisioning/qtci-linux-RHEL-7.4-x86_64/003-install-devtoolset6.sh → coin/provisioning/qtci-linux-RHEL-7.4-x86_64/003-install-devtoolset.sh

@@ -34,7 +34,7 @@
 #############################################################################
 
 sudo yum-config-manager --enable rhel-server-rhscl7-rpms
-sudo yum -y install devtoolset-6
+sudo yum -y install devtoolset-4
 
-echo "source /opt/rh/devtoolset-6/enable" >> ~/.bashrc
+echo "source /opt/rh/devtoolset-4/enable" >> ~/.bashrc
 

coin/provisioning/qtci-linux-RHEL-7.4-x86_64/010-openssl_for_android_linux.sh

@@ -33,5 +33,5 @@
 ##
 #############################################################################
 
-source /opt/rh/devtoolset-6/enable
+source /opt/rh/devtoolset-4/enable
 source "${BASH_SOURCE%/*}/../common/openssl_for_android_linux.sh"