build: remove AIX/ppc (32bit) dead code

* also dedup OS400 detection

PR-URL: #25523
Refs: https://github.com/nodejs/node/pull/25447/files/36839defcfaf7c46435e16fb1f0da006f3ebe8ac#r247378894
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>

Author: refack

common.gypi

@@ -116,28 +116,8 @@
             'msvs_configuration_platform': 'x64',
           }],
           ['OS=="aix"', {
-            'variables': {'real_os_name': '<!(uname -s)',},
             'cflags': [ '-gxcoff' ],
             'ldflags': [ '-Wl,-bbigtoc' ],
-            'conditions': [
-              ['target_arch=="ppc64"', {
-                'ldflags': [
-                  '-Wl,-blibpath:/usr/lib:/lib:'
-                    '/opt/freeware/lib/pthread/ppc64'
-                ],
-              }],
-              ['target_arch=="ppc"', {
-                'ldflags': [
-                  '-Wl,-blibpath:/usr/lib:/lib:/opt/freeware/lib/pthread'
-                ],
-              }],
-              ['"<(real_os_name)"=="OS400"', {
-                'ldflags': [
-                  '-Wl,-blibpath:/QOpenSys/pkgs/lib:/QOpenSys/usr/lib',
-                  '-Wl,-brtl',
-                ],
-              }],
-            ],
           }],
           ['OS == "android"', {
             'cflags': [ '-fPIE' ],
@@ -414,9 +394,9 @@
             'ldflags': [ '-m32' ],
           }],
           [ 'target_arch=="ppc64" and OS!="aix"', {
-	    'cflags': [ '-m64', '-mminimal-toc' ],
-	    'ldflags': [ '-m64' ],
-	   }],
+            'cflags': [ '-m64', '-mminimal-toc' ],
+            'ldflags': [ '-m64' ],
+          }],
           [ 'target_arch=="s390"', {
             'cflags': [ '-m31', '-march=z196' ],
             'ldflags': [ '-m31', '-march=z196' ],
@@ -431,38 +411,35 @@
             'cflags!': [ '-pthread' ],
             'ldflags!': [ '-pthread' ],
           }],
-          [ 'OS=="aix"', {
-            'variables': {'real_os_name': '<!(uname -s)',},
-            'conditions': [
-              [ 'target_arch=="ppc"', {
-                'ldflags': [
-                  '-Wl,-bmaxdata:0x60000000/dsa',
-                  '-Wl,-blibpath:/usr/lib:/lib:/opt/freeware/lib/pthread',
-                 ],
-              }],
-              [ 'target_arch=="ppc64"', {
-                'cflags': [ '-maix64' ],
-                'ldflags': [
-                  '-maix64',
-                  '-Wl,-blibpath:/usr/lib:/lib:'
-                    '/opt/freeware/lib/pthread/ppc64',
-                ],
-              }],
-              ['"<(real_os_name)"=="OS400"', {
-                'ldflags': [
-                  '-Wl,-blibpath:/QOpenSys/pkgs/lib:/QOpenSys/usr/lib',
-                  '-Wl,-brtl',
-                ],
-              }],
-            ],
-            'ldflags': [ '-Wl,-bbigtoc' ],
-            'ldflags!': [ '-rdynamic' ],
-          }],
           [ 'node_shared=="true"', {
             'cflags': [ '-fPIC' ],
           }],
         ],
       }],
+      [ 'OS=="aix"', {
+        'variables': {
+          # Used to differentiate `AIX` and `OS400`(IBM i).
+          'aix_variant_name': '<!(uname -s)',
+        },
+        'cflags': [ '-maix64', ],
+        'ldflags!': [ '-rdynamic', ],
+        'ldflags': [
+          '-Wl,-bbigtoc',
+          '-maix64',
+        ],
+        'conditions': [
+          [ '"<(aix_variant_name)"=="OS400"', {            # a.k.a. `IBM i`
+            'ldflags': [
+              '-Wl,-blibpath:/QOpenSys/pkgs/lib:/QOpenSys/usr/lib',
+              '-Wl,-brtl',
+            ],
+          }, {                                             # else it's `AIX`
+            'ldflags': [
+              '-Wl,-blibpath:/usr/lib:/lib:/opt/freeware/lib/pthread/ppc64',
+            ],
+          }],
+        ],
+      }],
       ['OS=="android"', {
         'target_conditions': [
           ['_toolset=="target"', {

node.gyp

@@ -1044,34 +1044,13 @@
 
   'conditions': [
     [ 'OS=="aix" and node_shared=="true"', {
-      'variables': {'real_os_name': '<!(uname -s)',},
       'targets': [
         {
           'target_name': 'node_aix_shared',
           'type': 'shared_library',
           'product_name': '<(node_core_target_name)',
           'ldflags': [ '--shared' ],
           'product_extension': '<(shlib_suffix)',
-          'conditions': [
-            ['target_arch=="ppc64"', {
-              'ldflags': [
-                '-Wl,-blibpath:/usr/lib:/lib:'
-                  '/opt/freeware/lib/pthread/ppc64'
-              ],
-            }],
-            ['target_arch=="ppc"', {
-              'ldflags': [
-                '-Wl,-blibpath:/usr/lib:/lib:/opt/freeware/lib/pthread'
-              ],
-            }],
-            ['"<(real_os_name)"=="OS400"', {
-              'ldflags': [
-                '-Wl,-blibpath:/QOpenSys/pkgs/lib:/QOpenSys/usr/lib',
-                '-Wl,-bbigtoc',
-                '-Wl,-brtl',
-              ],
-            }],
-          ],
           'includes': [
             'node.gypi'
           ],