configure.ac: Fix compilation of Haiku's C++ convenience library
Commit 9a1bc8cafb ("build: Require C11 to build and clean up
autoconfig/automake files") added the language standard compiler option
to the AM_CFLAGS and AM_CXXFLAGS. Placing it in the latter is incorrect
as compiling C++ source with the C11 language standard does not make
sense.
Fix this by determining which C11 dialect (GNU or C) the compiler
supports and then constructing the compiler option from that.
Also restrict LT_LDFLAGS to the final libusb library (as was done
previously) since libtool complains about versioning options for
convenience libraries.
Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>
libusb is a library for USB device access from Linux, macOS, Windows, OpenBSD/NetBSD, Haiku and Solaris userspace. It is written in C (Haiku backend in C++) and licensed under the GNU Lesser General Public License version 2.1 or, at your option, any later version (see COPYING).
libusb is abstracted internally in such a way that it can hopefully be ported to other operating systems. Please see the PORTING file for more information.
libusb homepage: http://libusb.info/
Developers will wish to consult the API documentation: http://api.libusb.info
Use the mailing list for questions, comments, etc: http://mailing-list.libusb.info
(Please use the mailing list rather than mailing developers directly)