refactor: switch to c++14 when building with gyp

NodeJS 16 onwards no longer supports building with c++11

See nodejs/node#38367

common.gypi

@@ -105,7 +105,7 @@
       [ 'OS in "linux freebsd openbsd solaris android"', {
         'cflags': [ '-Wall', '-Wextra', '-Wno-unused-parameter', '-Wno-comment' ],
         'cflags_cc!': [ '-fno-rtti', '-fno-exceptions' ],
-        'cflags_cc': [ '-std=c++11' ],
+        'cflags_cc': [ '-std=c++14' ],
         'ldflags': [ '-rdynamic' ],
         'target_conditions': [
           ['_type=="static_library"', {
@@ -139,7 +139,7 @@
           'OTHER_CFLAGS': [
             '-fno-strict-aliasing',
           ],
-          'CLANG_CXX_LANGUAGE_STANDARD': 'c++11',
+          'CLANG_CXX_LANGUAGE_STANDARD': 'c++14',
           'CLANG_CXX_LIBRARY': 'libc++',
           'WARNING_CFLAGS': [
             '-Wall',