npm: fix node and npm default directory conflict

Fixes [YOCTO #13349]

When dealing with node modules which have declared "bin" files [1], npm
will create a link in '/usr/bin' with a relative link to
'../lib/node_modules/<module bin file>'.

The commits e9270af429 and
2713d9bcc3 explicitely use
'/usr/lib/node/' as install directory, but does not care about the "bin"
symbolic linked files.

In order to keep valid links, and to keep it as simple as possible, the
path '/usr/lib/node_modules/' is used as install directory for npm. And
a symbolic link is created to have a valid '/usr/lib/node/' path, needed
for node.

[1]: https://docs.npmjs.com/files/package.json#bin

(From OE-Core rev: 67846b3b2d2d45401d500bff5cf3d4d71c003f7a)

Signed-off-by: Jean-Marie LEMETAYER <jean-marie.lemetayer@savoirfairelinux.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/npm.bbclass

@@ -10,7 +10,7 @@ def node_pkgname(d):
 
 NPMPN ?= "${@node_pkgname(d)}"
 
-NPM_INSTALLDIR = "${libdir}/node/${NPMPN}"
+NPM_INSTALLDIR = "${libdir}/node_modules/${NPMPN}"
 
 # function maps arch names to npm arch names
 def npm_oe_arch_map(target_arch, d):
@@ -55,7 +55,7 @@ npm_do_install() {
 	mkdir -p ${D}${libdir}/node_modules
 	local NPM_PACKFILE=$(npm pack .)
 	npm install --prefix ${D}${prefix} -g --arch=${NPM_ARCH} --target_arch=${NPM_ARCH} --production --no-registry ${NPM_PACKFILE}
-	mv ${D}${libdir}/node_modules ${D}${libdir}/node
+	ln -fs node_modules ${D}${libdir}/node
 	if [ -d ${D}${prefix}/etc ] ; then
 		# This will be empty
 		rmdir ${D}${prefix}/etc
@@ -85,6 +85,8 @@ python populate_packages_prepend () {
 }
 
 FILES_${PN} += " \
+    ${bindir} \
+    ${libdir}/node \
     ${NPM_INSTALLDIR} \
 "