AIX bootstrap failure

[Dave Love]

On rs6000-ibm-aix4.1.4.0 the 311097 snapshot fails to bootstrap with
native tools:

	stage1/xgcc -Bstage1/ -c  -DIN_GCC    -O2 -g   -DHAVE_CONFIG_H     -I. -I. -I./config rtl.c
	cc  -DIN_GCC    -O2 -g   -DHAVE_CONFIG_H   -o genattr  genattr.o rtl.o ` case "obstack.o" in ?*) echo obstack.o ;; esac ` ` case "cc"@"alloca.o" in "cc"@?*) echo alloca.o ;; esac ` ` case "" in ?*) echo  ;; esac `   -lm -lld
ld: 0711-317 ERROR: Undefined symbol: .alloca
ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information.
make: The error code from the last command is 8.