Update doxygen and fix documentation (#5106)

Update Doxyfile to version 1.9.1

Re-enable doxygen CI checker

Fix some regular comments that should have been doc comments

Document void return types for some inline functions explicitly

Move start of some doxygen groups so they are included always, and not left
out of certain ifdefs

Ignore some doxygen warnings:
    Member (function) is not documented in headers
    Documented empty return type in headers
    Argument has multiple @param documentation sections

JerryScript-DCO-1.0-Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

jerry-core/ecma/base/ecma-alloc.c

@@ -61,6 +61,8 @@ ecma_alloc_number (void)
 
 /**
  * Dealloc memory from an ecma-number
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_number (ecma_number_t *number_p) /**< number to be freed */
@@ -85,6 +87,8 @@ ecma_alloc_object (void)
 
 /**
  * Dealloc memory from an ecma-object
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_object (ecma_object_t *object_p) /**< object to be freed */
@@ -113,6 +117,8 @@ ecma_alloc_extended_object (size_t size) /**< size of object */
 
 /**
  * Dealloc memory of an extended object
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_extended_object (ecma_object_t *object_p, /**< extended object */
@@ -142,6 +148,8 @@ ecma_alloc_string (void)
 
 /**
  * Dealloc memory from ecma-string descriptor
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_string (ecma_string_t *string_p) /**< string to be freed */
@@ -170,6 +178,8 @@ ecma_alloc_extended_string (void)
 
 /**
  * Dealloc memory from extended ecma-string descriptor
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_extended_string (ecma_extended_string_t *ext_string_p) /**< extended string to be freed */
@@ -198,6 +208,8 @@ ecma_alloc_external_string (void)
 
 /**
  * Dealloc memory from external ecma-string descriptor
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_external_string (ecma_external_string_t *ext_string_p) /**< external string to be freed */
@@ -226,6 +238,8 @@ ecma_alloc_string_buffer (size_t size) /**< size of string */
 
 /**
  * Dealloc memory of a string with character data
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_string_buffer (ecma_string_t *string_p, /**< string with data */
@@ -255,6 +269,8 @@ ecma_alloc_property_pair (void)
 
 /**
  * Dealloc memory of an ecma-property
+ *
+ * @return void
  */
 extern inline void JERRY_ATTR_ALWAYS_INLINE
 ecma_dealloc_property_pair (ecma_property_pair_t *property_pair_p) /**< property pair to be freed */