Add coverity scan to CI and fix warnings (#3400)

* Move callback function in thread_pool ctor

* Added const qualifiers to logger.h

* Remove unused includes from file_helper-inl.h

* Fix comments and remove unused include from helpers-inl.h

* Fix typo in comment for set_default_logger method.

* Use `std::move` for `old_logger` in `set_default_logger`.

* Use std::move in example

* Wrap `main` content in try block for exception safety.

* Added coverity to ci

include/spdlog/details/file_helper-inl.h

@@ -11,10 +11,8 @@
 #include <spdlog/details/os.h>
 
 #include <cerrno>
-#include <chrono>
 #include <cstdio>
 #include <string>
-#include <thread>
 #include <tuple>
 
 namespace spdlog {

include/spdlog/details/registry-inl.h

@@ -101,7 +101,7 @@ SPDLOG_INLINE std::shared_ptr<logger> registry::default_logger() {
 SPDLOG_INLINE logger *registry::get_default_raw() { return default_logger_.get(); }
 
 // set default logger.
-// default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
+// the default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
 SPDLOG_INLINE void registry::set_default_logger(std::shared_ptr<logger> new_default_logger) {
     std::lock_guard<std::mutex> lock(logger_map_mutex_);
     if (new_default_logger != nullptr) {

include/spdlog/details/thread_pool-inl.h

@@ -35,7 +35,7 @@ SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
 SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
                                        size_t threads_n,
                                        std::function<void()> on_thread_start)
-    : thread_pool(q_max_items, threads_n, on_thread_start, [] {}) {}
+    : thread_pool(q_max_items, threads_n, std::move(on_thread_start), [] {}) {}
 
 SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items, size_t threads_n)
     : thread_pool(q_max_items, threads_n, [] {}, [] {}) {}
@@ -94,8 +94,7 @@ void SPDLOG_INLINE thread_pool::worker_loop_() {
 }
 
 // process next message in the queue
-// return true if this thread should still be active (while no terminate msg
-// was received)
+// returns true if this thread should still be active (while no terminated msg was received)
 bool SPDLOG_INLINE thread_pool::process_next_msg_() {
     async_msg incoming_async_msg;
     q_.dequeue(incoming_async_msg);