Merge pull request #87 from dmuir/master

Fix integer overflow detected by fuzz test.

Author: jkuhlmann

cgltf.h

@@ -1711,7 +1711,7 @@ cgltf_size cgltf_accessor_read_index(const cgltf_accessor* accessor, cgltf_size
 #define CGLTF_CHECK_TOKTYPE(tok_, type_) if ((tok_).type != (type_)) { return CGLTF_ERROR_JSON; }
 #define CGLTF_CHECK_KEY(tok_) if ((tok_).type != JSMN_STRING || (tok_).size == 0) { return CGLTF_ERROR_JSON; } /* checking size for 0 verifies that a value follows the key */
 
-#define CGLTF_PTRINDEX(type, idx) (type*)(cgltf_size)(idx + 1)
+#define CGLTF_PTRINDEX(type, idx) (type*)((cgltf_size)idx + 1)
 #define CGLTF_PTRFIXUP(var, data, size) if (var) { if ((cgltf_size)var > size) { return CGLTF_ERROR_JSON; } var = &data[(cgltf_size)var-1]; }
 #define CGLTF_PTRFIXUP_REQ(var, data, size) if (!var || (cgltf_size)var > size) { return CGLTF_ERROR_JSON; } var = &data[(cgltf_size)var-1];