py/gc: Adjust gc_alloc() signature to be able to accept multiple flags.

The older "bool has_finaliser" gets recast as GC_ALLOC_FLAG_HAS_FINALISER=1
so this is a backwards compatible change to the signature.  Since bool gets
implicitly converted to 1 this patch doesn't include conversion of all
calls.

py/gc.c

@@ -433,7 +433,8 @@ void gc_info(gc_info_t *info) {
     GC_EXIT();
 }
 
-void *gc_alloc(size_t n_bytes, bool has_finaliser) {
+void *gc_alloc(size_t n_bytes, unsigned int alloc_flags) {
+    bool has_finaliser = alloc_flags & GC_ALLOC_FLAG_HAS_FINALISER;
     size_t n_blocks = ((n_bytes + BYTES_PER_BLOCK - 1) & (~(BYTES_PER_BLOCK - 1))) / BYTES_PER_BLOCK;
     DEBUG_printf("gc_alloc(" UINT_FMT " bytes -> " UINT_FMT " blocks)\n", n_bytes, n_blocks);
 

py/gc.h

@@ -48,7 +48,11 @@ void gc_collect_end(void);
 // Use this function to sweep the whole heap and run all finalisers
 void gc_sweep_all(void);
 
-void *gc_alloc(size_t n_bytes, bool has_finaliser);
+enum {
+    GC_ALLOC_FLAG_HAS_FINALISER = 1,
+};
+
+void *gc_alloc(size_t n_bytes, unsigned int alloc_flags);
 void gc_free(void *ptr); // does not call finaliser
 size_t gc_nbytes(const void *ptr);
 void *gc_realloc(void *ptr, size_t n_bytes, bool allow_move);