make+tools: remove goacc, use Go 1.20 builtin functionality

Starting with Go 1.20 the -coverprofile flag does the same that GOACC
did before.

Makefile

@@ -1,5 +1,4 @@
 PKG := github.com/lightningnetwork/lnd
-ESCPKG := github.com\/lightningnetwork\/lnd
 MOBILE_PKG := $(PKG)/mobile
 TOOLS_DIR := tools
 
@@ -7,14 +6,12 @@ GOCC ?= go
 PREFIX ?= /usr/local
 
 BTCD_PKG := github.com/btcsuite/btcd
-GOACC_PKG := github.com/ory/go-acc
 GOIMPORTS_PKG := github.com/rinchsan/gosimports/cmd/gosimports
 
 GO_BIN := ${GOPATH}/bin
 BTCD_BIN := $(GO_BIN)/btcd
 GOIMPORTS_BIN := $(GO_BIN)/gosimports
 GOMOBILE_BIN := $(GO_BIN)/gomobile
-GOACC_BIN := $(GO_BIN)/go-acc
 
 MOBILE_BUILD_DIR :=${GOPATH}/src/$(MOBILE_PKG)/build
 IOS_BUILD_DIR := $(MOBILE_BUILD_DIR)/ios
@@ -92,10 +89,6 @@ all: scratch check install
 # ============
 # DEPENDENCIES
 # ============
-$(GOACC_BIN):
-	@$(call print, "Installing go-acc.")
-	cd $(TOOLS_DIR); $(GOCC) install -trimpath -tags=tools $(GOACC_PKG)
-
 $(BTCD_BIN):
 	@$(call print, "Installing btcd.")
 	cd $(TOOLS_DIR); $(GOCC) install -trimpath $(BTCD_PKG)
@@ -258,9 +251,9 @@ unit-debug: $(BTCD_BIN)
 	$(UNIT_DEBUG)
 
 #? unit-cover: Run unit tests in coverage mode
-unit-cover: $(GOACC_BIN)
+unit-cover:
 	@$(call print, "Running unit coverage tests.")
-	$(GOACC)
+	$(UNIT_COVER)
 
 #? unit-race: Run unit tests in race detector mode
 unit-race: