Raise minimum compiler versions

Supporting these is not reasonable anymore and effectively we didn't
do that anyway, brokenness was only noticed by chance and a PR to restore
support for gcc 5.x is ready now.

CMakeLists.txt

@@ -12,8 +12,8 @@ project(minetest)
 set(PROJECT_NAME_CAPITALIZED "Minetest")
 
 set(CMAKE_CXX_STANDARD 11)
-set(GCC_MINIMUM_VERSION "4.8")
-set(CLANG_MINIMUM_VERSION "3.4")
+set(GCC_MINIMUM_VERSION "5.1")
+set(CLANG_MINIMUM_VERSION "3.5")
 
 # Also remember to set PROTOCOL_VERSION in network/networkprotocol.h when releasing
 set(VERSION_MAJOR 5)
@@ -267,11 +267,6 @@ if(NOT USE_LUAJIT)
 	add_subdirectory(lib/bitop)
 endif()
 
-# JsonCpp doesn't compile well on GCC 4.8
-if(NOT USE_SYSTEM_JSONCPP)
-	set(GCC_MINIMUM_VERSION "4.9")
-endif()
-
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
 	if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "${GCC_MINIMUM_VERSION}")
 		message(FATAL_ERROR "Insufficient gcc version, found ${CMAKE_CXX_COMPILER_VERSION}. "

README.md

@@ -132,7 +132,7 @@ Compiling
 
 | Dependency | Version | Commentary |
 |------------|---------|------------|
-| GCC        | 4.9+    | Can be replaced with Clang 3.4+ |
+| GCC        | 5.1+    | or Clang 3.5+ |
 | CMake      | 3.5+    |            |
 | IrrlichtMt | -       | Custom version of Irrlicht, see https://github.com/minetest/irrlicht |
 | Freetype   | 2.0+    |            |