Rename INSTALL_PREFIX to DESTDIR and fix BINNAME

Author: tashian

Makefile

@@ -2,7 +2,7 @@
 # V=1 for verbose output.
 # BINNAME=step to change the name of the executable
 # PREFIX=bin/ to change the build output path
-# INSTALL_PREFIX=/usr/local/bin to change the install path
+# DESTDIR=/usr/local/bin to change the install path
 # GOOS_OVERRIDE="GOOS=linux GOARCH=arm GOARM=6" to change OS and arch
 # CGO_OVERRIDE="CGO_ENABLED=1" to enable CGO
 #
@@ -150,14 +150,14 @@ govulncheck:
 # Install
 #########################################
 
-INSTALL_PREFIX?=/usr/local/
+DESTDIR?=/usr/local/
 
-install: $(PREFIX)bin/step
-	$Q mkdir -p $(INSTALL_PREFIX)bin/
-	$Q install $(PREFIX)bin/step $(DESTDIR)$(INSTALL_PREFIX)bin/step
+install: $(PREFIX)bin/$(BINNAME)
+	$Q mkdir -p $(DESTDIR)bin/
+	$Q install $(PREFIX)bin/$(BINNAME) $(DESTDIR)bin/$(BINNAME)
 
 uninstall:
-	$Q rm -f $(DESTDIR)$(INSTALL_PREFIX)/bin/step
+	$Q rm -f $(DESTDIR)/bin/$(BINNAME)
 
 .PHONY: install uninstall
 
@@ -166,7 +166,7 @@ uninstall:
 #########################################
 
 clean:
-	$Q rm -f bin/step
+	$Q rm -f bin/$(BINNAME)
 	$Q rm -rf dist
 
 .PHONY: clean
@@ -182,7 +182,7 @@ define BUNDLE_MAKE
 	# $(2) -- Go Architecture (e.g. amd64, arm, arm64, etc.)
 	# $(3) -- Go ARM architectural family (e.g. 7, 8, etc.)
 	# $(4) -- Parent directory for executables generated by 'make'.
-	$Q GOOS_OVERRIDE='GOOS=$(1) GOARCH=$(2) GOARM=$(3)' PREFIX=$(4) make $(4)bin/step
+	$Q GOOS_OVERRIDE='GOOS=$(1) GOARCH=$(2) GOARM=$(3)' PREFIX=$(4) make $(4)bin/$(BINNAME)
 endef
 
 binary-linux-amd64: