build: compile with -std=gnu++14

The name ‘gnu++1y’ is deprecated.

Refs: https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html

PR-URL: #38504
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

common.gypi

@@ -375,7 +375,7 @@
       }],
       [ 'OS in "linux freebsd openbsd solaris android aix cloudabi"', {
         'cflags': [ '-Wall', '-Wextra', '-Wno-unused-parameter', ],
-        'cflags_cc': [ '-fno-rtti', '-fno-exceptions', '-std=gnu++1y' ],
+        'cflags_cc': [ '-fno-rtti', '-fno-exceptions', '-std=gnu++14' ],
         'defines': [ '__STDC_FORMAT_MACROS' ],
         'ldflags': [ '-rdynamic' ],
         'target_conditions': [
@@ -519,7 +519,7 @@
           ['clang==1', {
             'xcode_settings': {
               'GCC_VERSION': 'com.apple.compilers.llvm.clang.1_0',
-              'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++1y',  # -std=gnu++1y
+              'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++14',  # -std=gnu++14
               'CLANG_CXX_LIBRARY': 'libc++',
             },
           }],