build: change usage of `grep` for better compatibility

Makefile

@@ -23,7 +23,7 @@ ADDITION = go build -o w$(NAME).exe -trimpath -ldflags "-H windowsgui $(LDFLAGS)
 else
 OUTPUT = $(NAME)
 endif
-ifeq ($(shell echo "$(GOARCH)" | grep -Pq "(mips|mipsle)" && echo true),true) # 
+ifeq ($(shell echo "$(GOARCH)" | grep -Eq "(mips|mipsle)" && echo true),true) # 
 ADDITION = GOMIPS=softfloat go build -o $(NAME)_softfloat -trimpath -ldflags "$(LDFLAGS)" -v $(MAIN)
 endif
 .PHONY: clean