pass C++11 flag to castxml

[mamoll]

Just putting in "-std=c++11" in cflags is not sufficient. Without this change, I get errors like these:

In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/stdexcept:45:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__config:234:20: error: 
      cannot combine with previous 'char16_t' declaration specifier
typedef __char16_t char16_t;
                   ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__config:235:20: error: 
      cannot combine with previous 'char32_t' declaration specifier
typedef __char32_t char32_t;
                   ^
2 errors generated.

This fix should probably generalized to cover C++14 and C++17 as well.

[iMichka]

Hi; thanks for the patch.

I was able to reproduce this. It happens as soon as you use #include <iostream> and use cflags="-std=c++11".

I'll merge the patch, and generalise it for C++14 and C++17 (probably in a more generic way, by looking for c++XX). I'll also be able to write a test for this.

Is this something you would need in a stable release soon ? I can create a 1.7.3 version with theses changes, and get it out in a week or two.

[mamoll]

I don't need this released soon. This is all part of an overhaul of another project (ompl) to be C++11-only. That will take some time. Thanks for offering, though!

[iMichka]

Ok. I added a test and allowed more c++ versions. I'll probably make a 1.7.3 version in a few weeks, so this will be added to it.