package/nodejs: fix parallel build

Unless told otherwise, ninja will spawn as many jobs as there are CPU
(plus 2). Nodejs is built with ninja, but it is a generic package, so
there is no variable (like with cmake-package) that passes the proper
number of parallel jobs as configured by the user.

As a consequence, the nodejs build will use as many CPU as are
available, possibly overcommitting the rsources the user expected to be
used.

Set the JOBS variableto limit that number.

Signed-off-by: Jens Maus <mail@jens-maus.de>
[yann.morin.1998@free.fr: reword commit log]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 84c24ab1b5a7d38b481b37a759480ff2273b499d)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/nodejs/nodejs.mk

@@ -46,14 +46,16 @@ HOST_NODEJS_MAKE_OPTS = \
 	CXXFLAGS="$(HOST_NODEJS_CXXFLAGS)" \
 	LDFLAGS.host="$(HOST_LDFLAGS)" \
 	NO_LOAD=cctest.target.mk \
-	PATH=$(@D)/bin:$(BR_PATH)
+	PATH=$(@D)/bin:$(BR_PATH) \
+	JOBS=$(BR2_JLEVEL)
 
 NODEJS_MAKE_OPTS = \
 	$(TARGET_CONFIGURE_OPTS) \
 	NO_LOAD=cctest.target.mk \
 	PATH=$(@D)/bin:$(BR_PATH) \
 	LDFLAGS="$(NODEJS_LDFLAGS)" \
-	LD="$(TARGET_CXX)"
+	LD="$(TARGET_CXX)" \
+	JOBS=$(BR2_JLEVEL)
 
 # nodejs's build system uses python which can be a symlink to an unsupported
 # python version (e.g. python 3.10 with nodejs 14.18.1). We work around this by