Set CC_FOR_TARGET when configuring cross binutils.

This is required to make the ld testsuite work correctly, as some tests
require a compiler.

Makefile.in

@@ -151,7 +151,8 @@ patches: $(addprefix $(srcdir)/patches/,$(PACKAGES))
 stamps/build-binutils-linux: $(srcdir)/riscv-binutils-gdb
 	rm -rf $@ $(notdir $@)
 	mkdir $(notdir $@)
-	cd $(notdir $@) && $</configure \
+# CC_FOR_TARGET is required for the ld testsuite.
+	cd $(notdir $@) && CC_FOR_TARGET=$(GLIBC_CC_FOR_TARGET) $</configure \
 		--target=$(LINUX_TUPLE) \
 		$(CONFIGURE_HOST) \
 		--prefix=$(INSTALL_DIR) \
@@ -329,7 +330,8 @@ stamps/build-gcc-linux-native: $(srcdir)/riscv-gcc stamps/build-gcc-linux-stage2
 stamps/build-binutils-newlib: $(srcdir)/riscv-binutils-gdb
 	rm -rf $@ $(notdir $@)
 	mkdir $(notdir $@)
-	cd $(notdir $@) && $</configure \
+# CC_FOR_TARGET is required for the ld testsuite.
+	cd $(notdir $@) && CC_FOR_TARGET=$(NEWLIB_CC_FOR_TARGET) $</configure \
 		--target=$(NEWLIB_TUPLE) \
 		$(CONFIGURE_HOST) \
 		--prefix=$(INSTALL_DIR) \