build.sh: accept --help (#1093)

Currently, the `--help` argument isn't supported:
```
$ ./build.sh --help
Invalid option or formatting, check --help: --help
```

Authors:
  - Mads R. B. Kristensen (https://github.com/madsbk)

Approvers:
  - Bradley Dice (https://github.com/bdice)

URL: #1093

build.sh

@@ -100,7 +100,7 @@ function ensureCMakeRan {
     fi
 }
 
-if hasArg -h; then
+if hasArg -h || hasArg --help; then
     echo "${HELP}"
     exit 0
 fi