[log]: Normal log works on Linux now

* also removed strlcpy dependency from log
* added Kconfig option for linux target

Closes IDF-3245

components/log/log_linux.c

@@ -0,0 +1,46 @@
+// Copyright 2010-2021 Espressif Systems (Shanghai) CO 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.
+
+#include <pthread.h>
+#include <time.h>
+#include <assert.h>
+#include <stdint.h>
+#include "esp_log_private.h"
+
+static pthread_mutex_t mutex1 = PTHREAD_MUTEX_INITIALIZER;
+
+void esp_log_impl_lock(void)
+{
+    assert(pthread_mutex_lock(&mutex1) == 0);
+}
+
+bool esp_log_impl_lock_timeout(void)
+{
+    esp_log_impl_lock();
+    return true;
+}
+
+void esp_log_impl_unlock(void)
+{
+    assert(pthread_mutex_unlock(&mutex1) == 0);
+}
+
+uint32_t esp_log_timestamp(void)
+{
+    struct timespec current_time;
+    int result = clock_gettime(CLOCK_MONOTONIC, &current_time);
+    assert(result == 0);
+    uint32_t seconds = current_time.tv_sec * 1000 + current_time.tv_nsec / 1000000;
+    return seconds;
+}