build: don't build deps/zlib if --shared-zlib set

Even if the --shared-zlib flag was used, the bundled deps/zlib was still
being compiled into the binary as it was required by the C++ test suite.

PR-URL: #10657
Fixes: #10649
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

Author: gibfahn

node.gyp

@@ -900,7 +900,6 @@
             'HAVE_INSPECTOR=1',
           ],
           'dependencies': [
-            'deps/zlib/zlib.gyp:zlib',
             'v8_inspector_compress_protocol_json#host'
           ],
           'include_dirs': [
@@ -913,6 +912,11 @@
             'test/cctest/test_inspector_socket_server.cc'
           ],
           'conditions': [
+            [ 'node_shared_zlib=="false"', {
+              'dependencies': [
+                'deps/zlib/zlib.gyp:zlib',
+              ]
+            }],
             [ 'node_shared_openssl=="false"', {
               'dependencies': [
                 'deps/openssl/openssl.gyp:openssl'