scripts: don't generate and install zsh completion when cross-compiling

scripts/Makefile.am

@@ -27,9 +27,17 @@ ZSH_COMPLETION_FUNCTION_FILENAME = _curl
 all-local: $(ZSH_COMPLETION_FUNCTION_FILENAME)
 
 $(ZSH_COMPLETION_FUNCTION_FILENAME): zsh.pl
+if CROSSCOMPILING
+	@echo "NOTICE: we can't generate zsh completion when cross-compiling!"
+else # if not cross-compiling:
 	@if ! test -x "$(PERL)"; then echo "No perl: can't install zsh.pl"; exit 0; fi
 	$(PERL) $(srcdir)/zsh.pl $(top_builddir)/src/curl > $@
+endif
 
 install-data-local:
+if CROSSCOMPILING
+	@echo "NOTICE: we can't install zsh completion when cross-compiling!"
+else # if not cross-compiling:
 	$(MKDIR_P) $(DESTDIR)$(ZSH_FUNCTIONS_DIR)
 	$(INSTALL_DATA) $(ZSH_COMPLETION_FUNCTION_FILENAME) $(DESTDIR)$(ZSH_FUNCTIONS_DIR)/$(ZSH_COMPLETION_FUNCTION_FILENAME)
+endif