[XXX not perfect since gotslot are allocated on a per-symbol basis but
not a per-symbol & addend tuple. This makes impossible to have separate
GOT entries to ___sF (stdin), ___sF+88 (stdout), and ___sF+176 (stderr)]
Add argument to md_fix_jmpslot indicating whether this the first (i.e
tranfer) jmpslot or not. Add better support for VAX (the VAX can support
pure text code; let ld that advantage of it). Checking in verified and
working versions of rtld VAX support routines.