Remove DESTDIR prefix from bin-install line

If using DESTDIR to package up Rakudo Star in an RPM or similar
format, the Makefile currently ends up writing the package build
directory into the shebang line of the installed scripts.  This
is probably not a good idea.

tools/build/Makefile.in

@@ -79,7 +79,7 @@ modules-install: rakudo-install
 	@echo "== Installing modules"
 	$(PERL) tools/build/module-install.pl $(DESTDIR)$(PERL6_INSTALL) $(DESTDIR)$(PERL6_LANG_DIR)/lib $(MODULES)
 	@echo "== Installing binaries"
-	$(PERL) tools/build/bin-install.pl $(DESTDIR)$(PERL6_INSTALL) $(DESTDIR)$(PARROT_BIN_DIR) modules/ufo/bin/ufo modules/panda/bin/panda modules/doc/bin/p6doc
+	$(PERL) tools/build/bin-install.pl $(PERL6_INSTALL) $(DESTDIR)$(PARROT_BIN_DIR) modules/ufo/bin/ufo modules/panda/bin/panda modules/doc/bin/p6doc
 
 modules-test:
 	$(PERL) tools/build/modules-test.pl $(CURDIR) $(DESTDIR)$(PERL6_INSTALL) modules/MODULES.txt