explicitly set C++ version to 14

This was already the case with MSVC which defaults to C++14. In the
case of clang, this was causing build failures as C++14 features are
used in the codebase. In the case of gcc, the libc++ used there is
non-standards conformant and exposes C++14 features to C++11.

This fixes compilation under FreeBSD which uses clang and libcxx as the
codebase introduced C++14 stuff recently.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

CMakeLists.txt

@@ -45,11 +45,9 @@ option(GIT_SUBMODULE "Check submodules during build" ON)
 ### COMPILER SETTINGS
 #
 #
-IF(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  set(CMAKE_CXX_STANDARD 11)
-  set(CMAKE_CXX_STANDARD_REQUIRED ON)
-  set(CXX_EXTENSIONS NO)
-ENDIF()
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
 
 IF(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-switch -Wno-parentheses-equality -Wno-deprecated-declarations -Wno-tautological-compare -Wno-unused-value -Wno-comment -Wno-unsequenced -Wno-logical-op-parentheses -Wno-literal-conversion")
@@ -62,7 +60,7 @@ IF(CMAKE_SYSTEM_NAME STREQUAL "NetBSD")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread")
 ENDIF()
 IF(CMAKE_COMPILER_IS_GNUCXX)
-  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wno-psabi -rdynamic")
+  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-psabi -rdynamic")
   #SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-switch")
   #ADD_DEFINITIONS( -Wall -O0 -ggdb )
   #ADD_DEFINITIONS( -Wfatal-errors -Wformat=2 -Werror=format-security )