gstallocator: Make alloc function take GstAllocationParams by const

The param argument passed to this function does not need to be modified.
Add const to enforce this at compile-time and emit a proper signature in
G-IR.

gst/gstallocator.c

@@ -290,7 +290,7 @@ gst_allocator_set_default (GstAllocator * allocator)
  */
 GstMemory *
 gst_allocator_alloc (GstAllocator * allocator, gsize size,
-    GstAllocationParams * params)
+    const GstAllocationParams * params)
 {
   GstMemory *mem;
   static GstAllocationParams defparams = { 0, 0, 0, 0, };
@@ -505,7 +505,7 @@ _sysmem_is_span (GstMemorySystem * mem1, GstMemorySystem * mem2, gsize * offset)
 
 static GstMemory *
 default_alloc (GstAllocator * allocator, gsize size,
-    GstAllocationParams * params)
+    const GstAllocationParams * params)
 {
   gsize maxsize = size + params->prefix + params->padding;
 

gst/gstallocator.h

@@ -144,7 +144,7 @@ struct _GstAllocatorClass {
 
   /*< public >*/
   GstMemory *  (*alloc)      (GstAllocator *allocator, gsize size,
-                              GstAllocationParams *params);
+                              const GstAllocationParams *params);
   void         (*free)       (GstAllocator *allocator, GstMemory *memory);
 
   /*< private >*/
@@ -181,7 +181,7 @@ void           gst_allocation_params_free    (GstAllocationParams *params);
 
 GST_API
 GstMemory *    gst_allocator_alloc           (GstAllocator * allocator, gsize size,
-                                              GstAllocationParams *params);
+                                              const GstAllocationParams *params);
 
 GST_API
 void           gst_allocator_free            (GstAllocator * allocator, GstMemory *memory);

gst/gstbuffer.c

@@ -878,7 +878,7 @@ gst_buffer_new (void)
  */
 GstBuffer *
 gst_buffer_new_allocate (GstAllocator * allocator, gsize size,
-    GstAllocationParams * params)
+    const GstAllocationParams * params)
 {
   GstBuffer *newbuf;
   GstMemory *mem;

gst/gstbuffer.h

@@ -291,7 +291,7 @@ GstBuffer * gst_buffer_new                 (void);
 
 GST_API
 GstBuffer * gst_buffer_new_allocate        (GstAllocator * allocator, gsize size,
-                                            GstAllocationParams * params);
+                                            const GstAllocationParams * params);
 GST_API
 GstBuffer * gst_buffer_new_wrapped_full    (GstMemoryFlags flags, gpointer data, gsize maxsize,
                                             gsize offset, gsize size, gpointer user_data,

tests/check/gst/gstmemory.c

@@ -586,7 +586,7 @@ typedef struct
 
 static GstMemory *
 _my_opaque_alloc (GstAllocator * allocator, gsize size,
-    GstAllocationParams * params)
+    const GstAllocationParams * params)
 {
   MyOpaqueMemory *mem = g_slice_new (MyOpaqueMemory);
   gsize maxsize = size + params->prefix + params->padding;

tests/examples/memory/my-memory.c

@@ -29,7 +29,8 @@ typedef struct
 
 
 static GstMemory *
-_my_alloc (GstAllocator * allocator, gsize size, GstAllocationParams * params)
+_my_alloc (GstAllocator * allocator, gsize size,
+    const GstAllocationParams * params)
 {
   MyMemory *mem;
   gsize maxsize = size + params->prefix + params->padding;

tests/examples/memory/my-vidmem.c

@@ -34,7 +34,8 @@ typedef struct
 
 
 static GstMemory *
-_my_alloc (GstAllocator * allocator, gsize size, GstAllocationParams * params)
+_my_alloc (GstAllocator * allocator, gsize size,
+    const GstAllocationParams * params)
 {
   g_warning ("Use my_vidmem_alloc() to allocate from this allocator");