fix(app): crop animated images on web with libwebp (#2947)

fluxer_app/rust/libfluxwebp/shim/stdlib.h

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#ifndef FLUXWEBP_STDLIB_H
+#define FLUXWEBP_STDLIB_H
+#include <stddef.h>
+void* fluxwebp_shim_malloc(size_t size);
+void* fluxwebp_shim_calloc(size_t nmemb, size_t size);
+void fluxwebp_shim_free(void* ptr);
+void fluxwebp_shim_qsort(void* base, size_t nitems, size_t size, int (*compar)(const void*, const void*));
+#define malloc(size) fluxwebp_shim_malloc(size)
+#define calloc(nmemb, size) fluxwebp_shim_calloc(nmemb, size)
+#define free(ptr) fluxwebp_shim_free(ptr)
+#define qsort(base, nitems, size, compar) fluxwebp_shim_qsort(base, nitems, size, compar)
+#define abort() __builtin_trap()
+static inline int abs(int x) { return x < 0 ? -x : x; }
+#endif