title: npm install --production and bcrypt issue for npm 6.2.0
body: <p>I am trying to perform “npm install —production” on a debian ec2 machine on aws.  The server is currently running node version 10.8.0 and nom version 6.2.0.  I am not sure if this is a version issue/conflict?  It seems as if it happens only for the bcrypt package.  It seems as if it is trying to compile the bcrypt code.  What is the cause of this issue and how can it be resolved?</p>
  
  <pre><code>&gt; bcrypt@3.0.0 install /home/admin/ProjectDir/node_modules/bcrypt
  &gt; node-pre-gyp install --fallback-to-build
  
  node-pre-gyp WARN Tried to download(404): https://github.com/kelektiv/node.bcrypt.js/releases/download/v3.0.0/bcrypt_lib-v3.0.0-node-v64-linux-x64-glibc.tar.gz 
  node-pre-gyp WARN Pre-built binaries not found for bcrypt@3.0.0 and node@10.8.0 (node-v64 ABI, glibc) (falling back to source compile with node-gyp) 
  make: Entering directory '/home/admin/ProjectDir/node_modules/bcrypt/build'
    CXX(target) Release/obj.target/bcrypt_lib/src/blowfish.o
    CXX(target) Release/obj.target/bcrypt_lib/src/bcrypt.o
    CXX(target) Release/obj.target/bcrypt_lib/src/bcrypt_node.o
  ../src/bcrypt_node.cc: In function ‘char {anonymous}::ToCharVersion(v8::Local&lt;v8::String&gt;)’:
  ../src/bcrypt_node.cc:66:30: warning: ‘v8::String::Utf8Value::Utf8Value(v8::Local&lt;v8::Value&gt;)’ is deprecated: Use Isolate version [-Wdeprecated-declarations]
     String::Utf8Value value(str);
                                ^
  In file included from /root/.node-gyp/10.8.0/include/node/v8.h:26:0,
                   from /root/.node-gyp/10.8.0/include/node/node.h:63,
                   from ../../nan/nan.h:51,
                   from ../src/bcrypt_node.cc:1:
  /root/.node-gyp/10.8.0/include/node/v8.h:2852:28: note: declared here
                     explicit Utf8Value(Local&lt;v8::Value&gt; obj));
                              ^
  /root/.node-gyp/10.8.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
     declarator __attribute__((deprecated(message)))
     ^~~~~~~~~~
    SOLINK_MODULE(target) Release/obj.target/bcrypt_lib.node
    COPY Release/bcrypt_lib.node
    COPY /home/admin/ProjectDir/node_modules/bcrypt/lib/binding/bcrypt_lib.node
    TOUCH Release/obj.target/action_after_build.stamp
  make: Leaving directory '/home/admin/ProjectDir/node_modules/bcrypt/build'
  
  &gt; sharp@0.20.5 install /home/admin/ProjectDir/node_modules/sharp
  &gt; (node install/libvips &amp;&amp; node install/dll-copy &amp;&amp; prebuild-install) || (node-gyp rebuild &amp;&amp; node install/dll-copy)
  
  info sharp Downloading https://github.com/lovell/sharp-libvips/releases/download/v8.6.1/libvips-8.6.1-linux-x64.tar.gz
  
  added 529 packages from 556 contributors and audited 1489 packages in 15.404s
  found 7 vulnerabilities (2 low, 5 moderate)
    run `npm audit fix` to fix them, or `npm audit` for details
  </code></pre>