bootstrap failure on alloca-less hosts

[Robert Lipe]

This native compiler has no intrinsic alloca.  (Acutally, it does but
autoconf doesn't know how to find it so most users won't bother to tell
it.)  

Removing the alloca construct and replacing it with
../libiberty/libiberty.a allows this hurdle to be crossed, but I have
a feeling this is wrong for some cross case or something.

        touch specs.ready; \
fi
/bin/cc  -DIN_GCC    -g   -DHAVE_CONFIG_H  -o gen-protos \
  gen-protos.o scan.o ` case "obstack.o" in ?*) echo obstack.o ;; esac ` ` case "alloca.o" in ?*) echo alloca.o ;; esac ` ` case "" in ?*) echo  ;; esac `  ` case "" in ?*) echo  ;; esac ` ` case "" in ?*) echo  ;; esac ` 
Undefined                       first referenced
 symbol                             in file
xmalloc                             alloca.o
UX:ld: ERROR: gen-protos: fatal error: Symbol referencing errors. No output written to gen-protos


This, of course, used to work...