egcs-980122: openvms/alpha patch 4

[Jeffrey A Law]

  In message <9801281059.AA29063@progis.de>you write:
  > This one is tricky: alpha/xm-vms.h defines USE_C_ALLOCA and
  > alpha/xm-alpha.h tests for USE_C_ALLOCA.
  > 
  > However, the cpu-specific file (xm-alpha.h) is included *before* the
  > os-specific file (xm-vms.h) in config.h.
  > 
  > A more general path is appropriate. But for the time being,
  > compililation on openVMS fails without this patch:
  > 
  > Thu Jan 28 12:52:56 1998  Klaus Kaempf  <kkaempf@progis.de>
  > 
  > 	* alpha/xm-alpha.h: don't include alloca.h on OPEN_VMS
Yes, I agree for this patch is OK.  We should find a better solution
long term.

I've installed it for now.
jeff