Drop support for C++98/C++03 (closes #1820)

extras/fuzzing/CMakeLists.txt

@@ -2,6 +2,9 @@
 # Copyright © 2014-2022, Benoit BLANCHON
 # MIT License
 
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 if(MSVC)
 	add_compile_options(-D_CRT_SECURE_NO_WARNINGS)
 endif()

extras/fuzzing/Makefile

@@ -1,6 +1,6 @@
 # CAUTION: this file is invoked by https://github.com/google/oss-fuzz
 
-CXXFLAGS += -I../../src -DARDUINOJSON_DEBUG=1
+CXXFLAGS += -I../../src -DARDUINOJSON_DEBUG=1 -std=c++11
 
 all: \
 	$(OUT)/json_fuzzer \