clean up result codes that are never used

clean up result codes that are never used

the following result codes are obsolete and have been removed
from result.h and result.c:

        - ISC_R_NOTHREADS
        - ISC_R_BOUND
        - ISC_R_NOTBOUND
        - ISC_R_NOTDIRECTORY
        - ISC_R_EMPTY
        - ISC_R_NOTBLOCKING
        - ISC_R_INPROGRESS
        - ISC_R_WOULDBLOCK

        - DNS_R_TOOMANYHOPS
        - DNS_R_NOREDATA
        - DNS_R_BADCKSUM
        - DNS_R_MOREDATA
        - DNS_R_NOVALIDDS
        - DNS_R_UNKNOWNOPT
        - DNS_R_NOVALIDKEY
        - DNS_R_NTACOVERED

        - DST_R_COMPUTESECRETFAILURE
        - DST_R_NORANDOMNESS
        - DST_R_NOCRYPTO