RFR: Report all GC status flags in hs_err

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/hserr-flags/webrev.01/

This consistently prints out GC flags in hs_err. Partial and full GC flags were just missing from
the printout. Also, flags are not exactly mutually exclusive, especially on failure and bug paths,
so let's report all of them without if-else-ing.

Testing: hotspot_fast_gc_shenandoah, eyeballing hs_errs

Thanks,
-Aleksey