Make disabling WASM_BIGINT explicit. (rhashimoto#241)

Co-authored-by: Roy Hashimoto <roy@shoestringresearch.com>

Author: rhashimoto

Makefile

@@ -54,6 +54,7 @@ EMFLAGS_COMMON = \
 	-s INVOKE_RUN \
 	-s ENVIRONMENT="web,worker" \
 	-s STACK_SIZE=512KB \
+	-s WASM_BIGINT=0 \
 	$(EMFLAGS_EXTRA)
 
 EMFLAGS_DEBUG = \