mesa: fix inconsistent function declaration, definitions

To silence MSVC warnings that the declaration and definitions
were different.

src/mesa/main/hash_table.c

@@ -110,8 +110,8 @@ entry_is_present(const struct hash_table *ht, struct hash_entry *entry)
 
 struct hash_table *
 _mesa_hash_table_create(void *mem_ctx,
-                        bool key_equals_function(const void *a,
-                                                 const void *b))
+                        bool (*key_equals_function)(const void *a,
+                                                    const void *b))
 {
    struct hash_table *ht;
 

src/mesa/main/set.c

@@ -103,8 +103,8 @@ entry_is_present(struct set_entry *entry)
 
 struct set *
 _mesa_set_create(void *mem_ctx,
-                 bool key_equals_function(const void *a,
-                                          const void *b))
+                 bool (*key_equals_function)(const void *a,
+                                             const void *b))
 {
    struct set *ht;