configure: Drop unused attribute checks

configure

@@ -1665,8 +1665,6 @@ TOOLCHAIN_FEATURES="
     as_func
     as_object_arch
     asm_mod_q
-    attribute_may_alias
-    attribute_packed
     blocks_extension
     ebp_available
     ebx_available
@@ -4295,14 +4293,6 @@ check_cc <<EOF && enable pragma_deprecated
 void foo(void) { _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"") }
 EOF
 
-check_cc <<EOF && enable attribute_packed
-struct { int x; } __attribute__((packed)) x;
-EOF
-
-check_cc <<EOF && enable attribute_may_alias
-union { int x; } __attribute__((may_alias)) x;
-EOF
-
 check_cc <<EOF || die "endian test failed"
 unsigned int endian = 'B' << 24 | 'I' << 16 | 'G' << 8 | 'E';
 EOF