fix(Makefile): npm path not properly set for cygwin (#1698)

Detect npm-path properly in cygwin (fixes windows build). Looks for '_NT' to detect if we are on cygwin or not.

Makefile

@@ -4,7 +4,14 @@ version=$(shell node -pe "require('./package.json').version")
 dist-out-dir = _dist
 pub-dir = $(dist-out-dir)/$(version)
 
-npm-bin = $(shell npm bin)
+
+# properly get npm-bin in cygwin (Eg. CYGWIN_NT-10.0)
+platform = $(shell uname -s)
+ifeq ($(findstring _NT,$(platform)),_NT)
+	npm-bin = $(shell cygpath -u $(shell npm bin))
+else
+	npm-bin = $(shell npm bin)
+endif
 
 build-out-dir = _build
 src-dir = client