Fix make run on windows

plugins/relx.mk

@@ -11,6 +11,7 @@ RELX_CONFIG ?= $(CURDIR)/relx.config
 RELX_URL ?= https://github.com/erlware/relx/releases/download/v3.19.0/relx
 RELX_OPTS ?=
 RELX_OUTPUT_DIR ?= _rel
+RELX_REL_EXT ?=
 RELX_TAR ?= 1
 
 ifdef SFX
@@ -73,8 +74,12 @@ RELX_REL := $(shell $(call erlang,$(get_relx_release.erl)))
 RELX_REL_NAME := $(word 1,$(RELX_REL))
 RELX_REL_VSN := $(word 2,$(RELX_REL))
 
+ifeq ($(PLATFORM),msys2)
+RELX_REL_EXT := .cmd
+endif
+
 run: all
-	$(verbose) $(RELX_OUTPUT_DIR)/$(RELX_REL_NAME)/bin/$(RELX_REL_NAME) console
+	$(verbose) $(RELX_OUTPUT_DIR)/$(RELX_REL_NAME)/bin/$(RELX_REL_NAME)$(RELX_REL_EXT) console
 
 help::
 	$(verbose) printf "%s\n" "" \