ld: sprintf sanitizer null destination pointer

* configure.ac (stpcpy): AC_CHECK_DECLS.
	* sysdep.h (stpcpy): Add fallback declaraion.
	* config.in: Regenerate.
	* configure: Regenerate.
	* emultempl/pe.em (open_dynamic_archive): Use
	stpcpy rather than sprintf plus strlen.
	* emultempl/pep.em (open_dynamic_archive): Likewise.
	* emultempl/xtensaelf.em (elf_xtensa_before_allocation): Use
	auto rather than malloc'd buffer.  Use sprintf count.
	* ldelf.c (ldelf_search_needed): Use memcpy in place of sprintf.
	* pe-dll.c (pe_process_import_defs): Use string already formed
	for alias match rather than recreating.

ld/configure

@@ -16771,6 +16771,16 @@ fi
 cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_ENVIRON $ac_have_decl
 _ACEOF
+ac_fn_c_check_decl "$LINENO" "stpcpy" "ac_cv_have_decl_stpcpy" "$ac_includes_default"
+if test "x$ac_cv_have_decl_stpcpy" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STPCPY $ac_have_decl
+_ACEOF