Updates for riscv support

* Target components pull in xtensa component directly
* Use CPU HAL where applicable
* Remove unnecessary xtensa headers
* Compilation changes necessary to support non-xtensa gcc types (ie int32_t/uint32_t is no
  longer signed/unsigned int).

Changes come from internal branch commit a6723fc

components/newlib/platform_include/sys/reent.h

@@ -0,0 +1,23 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include_next<sys/reent.h>
+
+/* This function is not part of the newlib API, it is defined in libc/stdio/local.h
+ * There is no nice way to get __cleanup member populated while avoiding __sinit,
+ * so extern declaration is used here.
+ */
+extern void _cleanup_r(struct _reent* r);