`upcxx -help` requires a CODEMODE

[Paul Hargrove]

The ChangeLog portion of our README advertises:

• upcxx has several new convenience options (see upcxx -help)

However, by default that demands a CODEMODE:

$ upcxx -help
upcxx: error: please specify exactly one of -O or -g, otherwise pass -codemode={O3,debug} or set UPCXX_CODEMODE={O3,debug}

Of course passing a -g or -O option gets past this error, but should not be necessary:

$ upcxx -g -help 2>&1 | wc -l
     670
$ upcxx -O -help 2>&1 | wc -l
     670

[Dan Bonachea]

fix issue #258: upcxx -help requires a CODEMODE

The -help option was added recently, so this bug did not affect any official release

→ <<cset 995da8ba7ae1>>