build: compile with -std=gnu++1y

It is necessary to enable more C++ features in order to build V8 6.4.

Author: targos

common.gypi

@@ -293,7 +293,7 @@
       }],
       [ 'OS in "linux freebsd openbsd solaris android aix cloudabi"', {
         'cflags': [ '-Wall', '-Wextra', '-Wno-unused-parameter', ],
-        'cflags_cc': [ '-fno-rtti', '-fno-exceptions', '-std=gnu++0x' ],
+        'cflags_cc': [ '-fno-rtti', '-fno-exceptions', '-std=gnu++1y' ],
         'ldflags': [ '-rdynamic' ],
         'target_conditions': [
           # The 1990s toolchain on SmartOS can't handle thin archives.
@@ -409,7 +409,7 @@
           ['clang==1', {
             'xcode_settings': {
               'GCC_VERSION': 'com.apple.compilers.llvm.clang.1_0',
-              'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++0x',  # -std=gnu++0x
+              'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++1y',  # -std=gnu++1y
               'CLANG_CXX_LIBRARY': 'libc++',
             },
           }],