$RELEASE_NAME Matching error

```
buildall.sh:222:  if [[ ! "$RELEASE_NAME" =~ CentOS.*5\.[[:digit:]] ]]; then
buildall.sh:293:if [[ ! "$RELEASE_NAME" =~ CentOS.*5\.[[:digit:]] ]]; then
source/llvm/build-source-tarball.sh:55:  if [[ ! "$RELEASE_NAME" =~ CentOS.*5\.[[:digit:]] ]]; then
```
`CentOS.*5\.[[:digit:]]` matches my CenOS 7.5 

```
# lsb_release -r -i
Distributor ID:	CentOS
Release:	7.5.1804
```