Upgrade mobile BUCK and .bzl files to use C++14

Summary:
Upgrade mobile `BUCK` and `.bzl` files to use C++14.

Let's see what happens.

Reviewed By: mzlee

Differential Revision: D14223329

fbshipit-source-id: ff642ca017103d9415c4d7f5beaf5ded07ef7ff1

csharp/BUCK

@@ -12,7 +12,7 @@ load(
     "yoga_dep",
 )
 
-COMPILER_FLAGS = BASE_COMPILER_FLAGS + ["-std=c++11"]
+COMPILER_FLAGS = BASE_COMPILER_FLAGS + ["-std=c++14"]
 
 fb_native.csharp_library(
     name = "yogalibnet46",

java/BUCK

@@ -18,7 +18,7 @@ yoga_cxx_library(
         "-Wall",
         "-Werror",
         "-Os",
-        "-std=c++11",
+        "-std=c++14",
     ],
     platforms = ANDROID,
     preprocessor_flags = [

lib/fb/BUCK

@@ -32,7 +32,7 @@ yoga_cxx_library(
         "-Wall",
         "-Werror",
         "-Wno-unused-parameter",
-        "-std=c++11",
+        "-std=c++14",
     ],
     platforms = (ANDROID,),
     visibility = ["PUBLIC"],

lib/gtest/BUCK

@@ -5,7 +5,7 @@
 load("//tools/build_defs/oss:yoga_defs.bzl", "YOGA_ROOTS", "subdir_glob", "yoga_cxx_library")
 
 COMPILER_FLAGS = [
-    "-std=c++11",
+    "-std=c++14",
     "-Wno-missing-prototypes",
 ]