Set C++11 as default C++ standard

Autoconf manual states that CXXFLAGS is a user variable and should not
be overriden, so I did not use AX_APPEND_COMPILE_FLAGS for this. Thus,
there are no checks if the compiler supports it, but also the builder can
override this flag by passing another flag that overrides it on the
command line. Okay, this is now way too theoretical.

Indeed, the override happens with ./configure 'CXXFLAGS=-std=c++17'
(both flags in final command line)

Do note:
- The standard was not explicitly set for some builds (thus compiler
default was used)
- The default on my own box is C++17
- I'm setting C++11 as that's required by my previous change. Upgrade to
  C++17 is deferred to until it becomes required.
- The use of CPPFLAGS could be reviewed... they may be used incorrectly
  (instead of CXXFLAGS). I would really like to get all the builders going
  before requirements are raised.
- CI cleanup would be nice
- wish 4144 would return.

****
mana/plus!128

0 files changed, 0 insertions, 0 deletions