Required to fix build with -buildmode=pie.

See: https://gitlab.alpinelinux.org/alpine/aports/-/issues/15809

diff -upr frp-0.54.0.orig/Makefile frp-0.54.0/Makefile
--- frp-0.54.0.orig/Makefile	2024-03-11 12:34:00.517804538 +0100
+++ frp-0.54.0/Makefile	2024-03-11 12:34:12.761172502 +0100
@@ -26,10 +26,10 @@ vet:
 	go vet ./...
 
 frps:
-	env CGO_ENABLED=0 go build -trimpath -ldflags "$(LDFLAGS)" -tags frps -o bin/frps ./cmd/frps
+	env go build -trimpath -ldflags "$(LDFLAGS)" -tags frps -o bin/frps ./cmd/frps
 
 frpc:
-	env CGO_ENABLED=0 go build -trimpath -ldflags "$(LDFLAGS)" -tags frpc -o bin/frpc ./cmd/frpc
+	env go build -trimpath -ldflags "$(LDFLAGS)" -tags frpc -o bin/frpc ./cmd/frpc
 
 test: gotest