tools: roughly port v8_abseil to gyp

Refs: v8/v8@fa7521e
Closes: nodejs/node-v8#211

Author: targos

tools/v8_gypfiles/features.gypi

@@ -452,6 +452,8 @@
       }],
       ['dcheck_always_on!=0', {
         'defines': ['DEBUG',],
+      }, {
+        'defines': ['NDEBUG',],
       }],
       ['v8_enable_verify_csa==1', {
         'defines': ['ENABLE_VERIFY_CSA',],