f add missing ''

Author: TheBlueMatt

genbindings.sh

@@ -47,7 +47,7 @@ if [ "$HOST_PLATFORM" = "host: x86_64-apple-darwin" ]; then
 
 	# stdlib.h doesn't exist in clang's wasm sysroot, and cbindgen
 	# doesn't actually use it anyway, so drop the import.
-	sed -i 's/#include <stdlib.h>//g' include/lightning.h
+	sed -i '' 's/#include <stdlib.h>//g' include/lightning.h
 else
 	sed -i 's/typedef LDKnative.*Import.*LDKnative.*;//g' include/lightning.h