lib: enable support for zoslib on z/OS

Check if zos-base.h is in the directory identified by environment
variable ZOSLIB_INCLUDES if set; otherwise search for it from a set of
candidates under nodeRootDir. Then pass it as
-Dzoslib_include_dir=<path-found> to gyp_main.py for use in common.gypi
to set 'includes_dir' when compiling addons.

Co-authored-by: Gaby Baghdadi <baghdadi@ca.ibm.com>

lib/configure.js

@@ -213,6 +213,44 @@ function configure (gyp, argv, callback) {
       }
     }
 
+    // For z/OS we need to set up the path to zoslib include directory,
+    // which contains headers included in v8config.h.
+    var zoslibIncDir
+    if (process.platform === 'os390') {
+      logprefix = "find zoslib's zos-base.h:"
+      let msg
+      var zoslibIncPath = process.env.ZOSLIB_INCLUDES
+      if (zoslibIncPath) {
+        zoslibIncPath = findAccessibleSync(logprefix, zoslibIncPath, ['zos-base.h'])
+        if (zoslibIncPath === undefined) {
+          msg = msgFormat('Could not find zos-base.h file in the directory set ' +
+                          'in ZOSLIB_INCLUDES environment variable: %s; set it ' +
+                          'to the correct path, or unset it to search %s', process.env.ZOSLIB_INCLUDES, nodeRootDir)
+        }
+      } else {
+        candidates = [
+          'include/node/zoslib/zos-base.h',
+          'include/zoslib/zos-base.h',
+          'zoslib/include/zos-base.h',
+          'install/include/node/zoslib/zos-base.h'
+        ]
+        zoslibIncPath = findAccessibleSync(logprefix, nodeRootDir, candidates)
+        if (zoslibIncPath === undefined) {
+          msg = msgFormat('Could not find any of %s in directory %s; set ' +
+                          'environmant variable ZOSLIB_INCLUDES to the path ' +
+                          'that contains zos-base.h', candidates.toString(), nodeRootDir)
+        }
+      }
+      if (zoslibIncPath !== undefined) {
+        zoslibIncDir = path.dirname(zoslibIncPath)
+        log.verbose(logprefix, "Found zoslib's zos-base.h in: %s", zoslibIncDir)
+      } else if (release.version.split('.')[0] >= 16) {
+        // zoslib is only shipped in Node v16 and above.
+        log.error(logprefix, msg)
+        return callback(new Error(msg))
+      }
+    }
+
     // this logic ported from the old `gyp_addon` python file
     var gypScript = path.resolve(__dirname, '..', 'gyp', 'gyp_main.py')
     var addonGypi = path.resolve(__dirname, '..', 'addon.gypi')
@@ -240,6 +278,9 @@ function configure (gyp, argv, callback) {
       argv.push('-Dnode_root_dir=' + nodeDir)
       if (process.platform === 'aix' || process.platform === 'os390') {
         argv.push('-Dnode_exp_file=' + nodeExpFile)
+        if (process.platform === 'os390' && zoslibIncDir) {
+          argv.push('-Dzoslib_include_dir=' + zoslibIncDir)
+        }
       }
       argv.push('-Dnode_gyp_dir=' + nodeGypDir)