Fix logging related issues (#4971)

PR #4907 moved the log level into the engine context, however this caused
issues with logging without the engine being initialized. This commit
reverts the log level to be a static variable.

This commit also implements missing format specifiers for jerry_log.

JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai dbatyai@inf.u-szeged.hu

jerry-core/jrt/jrt.h

@@ -117,6 +117,9 @@ void JERRY_ATTR_NORETURN jerry_unreachable (const char *file, const char *functi
  */
 void JERRY_ATTR_NORETURN jerry_fatal (jerry_fatal_code_t code);
 
+jerry_log_level_t jerry_jrt_get_log_level (void);
+void jerry_jrt_set_log_level (jerry_log_level_t level);
+
 /*
  * Logging
  */