Added ccache volume mapping to Docker scripts.

scripts/jenkins/clang.groovy

@@ -9,7 +9,7 @@ node('docker')
 
 	// Multiple configurations are build in parallel
 	parallel linux: {
-		docker.image('ogs6/clang-ogs-base:latest').inside
+		docker.image('ogs6/clang-ogs-base:latest').inside('-v /home/core/.ccache:/usr/src/.ccache')
 		{
 			catchError {
 				build 'build', '-DOGS_ADDRESS_SANITIZER=ON -DOGS_UNDEFINED_BEHAVIOR_SANITIZER=ON', ''

scripts/jenkins/gcc.groovy

@@ -8,7 +8,7 @@ node('docker')
   	}
 
 	stage 'Build'
-	docker.image('ogs6/gcc-ogs-base:latest').inside {
+	docker.image('ogs6/gcc-ogs-base:latest').inside('-v /home/core/.ccache:/usr/src/.ccache') {
 		build 'build', '', 'package tests ctest'
 	}