build: do not pass target toolchain flags to host toolchain

Fixes target toolchain arguments being passed to the host toolchain when
cross-compiling. For example, -m64 is not available on aarch64.

PR-URL: #48597
Reviewed-By: Richard Lau <rlau@redhat.com>

Author: tie

common.gypi

@@ -411,28 +411,56 @@
             'cflags': [ '-I/usr/local/include' ],
             'ldflags': [ '-Wl,-z,wxneeded' ],
           }],
-        ],
-        'conditions': [
-          [ 'target_arch=="ia32"', {
-            'cflags': [ '-m32' ],
-            'ldflags': [ '-m32' ],
-          }],
-          [ 'target_arch=="x64"', {
-            'cflags': [ '-m64' ],
-            'ldflags': [ '-m64' ],
-          }],
-          [ 'target_arch=="ppc" and OS not in "aix os400"', {
-            'cflags': [ '-m32' ],
-            'ldflags': [ '-m32' ],
-          }],
-          [ 'target_arch=="ppc64" and OS not in "aix os400"', {
-            'cflags': [ '-m64', '-mminimal-toc' ],
-            'ldflags': [ '-m64' ],
+          ['_toolset=="host"', {
+            'conditions': [
+              [ 'host_arch=="ia32"', {
+                'cflags': [ '-m32' ],
+                'ldflags': [ '-m32' ],
+              }],
+              [ 'host_arch=="x64"', {
+                'cflags': [ '-m64' ],
+                'ldflags': [ '-m64' ],
+              }],
+              [ 'host_arch=="ppc" and OS not in "aix os400"', {
+                'cflags': [ '-m32' ],
+                'ldflags': [ '-m32' ],
+              }],
+              [ 'host_arch=="ppc64" and OS not in "aix os400"', {
+                'cflags': [ '-m64', '-mminimal-toc' ],
+                'ldflags': [ '-m64' ],
+              }],
+              [ 'host_arch=="s390x" and OS=="linux"', {
+                'cflags': [ '-m64', '-march=z196' ],
+                'ldflags': [ '-m64', '-march=z196' ],
+              }],
+            ],
           }],
-          [ 'target_arch=="s390x" and OS=="linux"', {
-            'cflags': [ '-m64', '-march=z196' ],
-            'ldflags': [ '-m64', '-march=z196' ],
+          ['_toolset=="target"', {
+            'conditions': [
+              [ 'target_arch=="ia32"', {
+                'cflags': [ '-m32' ],
+                'ldflags': [ '-m32' ],
+              }],
+              [ 'target_arch=="x64"', {
+                'cflags': [ '-m64' ],
+                'ldflags': [ '-m64' ],
+              }],
+              [ 'target_arch=="ppc" and OS not in "aix os400"', {
+                'cflags': [ '-m32' ],
+                'ldflags': [ '-m32' ],
+              }],
+              [ 'target_arch=="ppc64" and OS not in "aix os400"', {
+                'cflags': [ '-m64', '-mminimal-toc' ],
+                'ldflags': [ '-m64' ],
+              }],
+              [ 'target_arch=="s390x" and OS=="linux"', {
+                'cflags': [ '-m64', '-march=z196' ],
+                'ldflags': [ '-m64', '-march=z196' ],
+              }],
+            ],
           }],
+        ],
+        'conditions': [
           [ 'OS=="solaris"', {
             'cflags': [ '-pthreads' ],
             'ldflags': [ '-pthreads' ],