build: do not define ZLIB_CONST

This define is not available in zlib prior to version 1.2.5.2. See
https://github.com/nodejs/node/issues/9110 for details. Workaround the
build breakage reported by casting away const in src/inspector_agent.cc
instead.

PR-URL: https://github.com/nodejs/node/pull/9122
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rod Vagg <rod@vagg.org>

deps/zlib/zlib.gyp

@@ -12,7 +12,6 @@
         {
           'target_name': 'zlib',
           'type': 'static_library',
-          'defines': [ 'ZLIB_CONST' ],
           'sources': [
             'adler32.c',
             'compress.c',
@@ -45,7 +44,6 @@
             '.',
           ],
           'direct_dependent_settings': {
-            'defines': [ 'ZLIB_CONST' ],
             'include_dirs': [
               '.',
             ],
@@ -74,12 +72,10 @@
           'direct_dependent_settings': {
             'defines': [
               'USE_SYSTEM_ZLIB',
-              'ZLIB_CONST',
             ],
           },
           'defines': [
             'USE_SYSTEM_ZLIB',
-            'ZLIB_CONST',
           ],
           'link_settings': {
             'libraries': [

node.gyp

@@ -477,8 +477,6 @@
         }],
         [ 'node_shared_zlib=="false"', {
           'dependencies': [ 'deps/zlib/zlib.gyp:zlib' ],
-        }, {
-          'defines': [ 'ZLIB_CONST' ],
         }],
 
         [ 'node_shared_http_parser=="false"', {

src/inspector_agent.cc

@@ -176,7 +176,7 @@ void SendProtocolJson(InspectorSocket* socket) {
       PROTOCOL_JSON[0] * 0x10000u +
       PROTOCOL_JSON[1] * 0x100u +
       PROTOCOL_JSON[2];
-  strm.next_in = PROTOCOL_JSON + 3;
+  strm.next_in = const_cast<uint8_t*>(PROTOCOL_JSON + 3);
   strm.avail_in = sizeof(PROTOCOL_JSON) - 3;
   std::vector<char> data(kDecompressedSize);
   strm.next_out = reinterpret_cast<Byte*>(&data[0]);