RFR (M): Enable HotSpot build with Clang

[BILL PITTORE]

I've run into some problems trying to build linux-i586-slowdebug and I 
think it's because of the following in gcc.make

Right now we have this:

   ifeq ($(DEBUG_CFLAGS/$(BUILDARCH)),)
       ifeq ($(USE_CLANG), true)
         # Clang doesn't understand -gstabs
         OPT_CFLAGS += -g
       else
         OPT_CFLAGS += -gstabs
       endif
   endif

I think the above should be:
  ifeq ($(DEBUG_CFLAGS/$(BUILDARCH)),)
       ifeq ($(USE_CLANG), true)
         # Clang doesn't understand -gstabs
         DEBUG_CFLAGS += -g
       else
         DEBUG_CFLAGS += -gstabs
       endif
   endif

If I do that then I'm able to debug with gdb as before. Should I file a bug on this or
is it something already discovered?

thanks,
bill