This patch switches code to SPDX one-line license identifiers according to
https://spdx.dev/learn/handling-license-info/
and replacing long license text headers.
I used C++ format on the first line in style
// SPDX-License-Identifier: <id>
except exported libcryptsetup.h, when only C comments are used.
The only additional changes are:
- switch backend utf8.c from LGPL2+ to LGPL2.1+ (as in systemd)
- add some additional formatting lines.
When compiled with enforced ISO C (e.g. -std=c11) 'asm' inline
does not compile (it's GNU extension). Use __asm__ inline assembly
with GCC and clang compliers instead.
Fixes: #786.
Starting with GCC10 and LTO enabled, current symbols
versioning hack does not work anymore. This patch
reflects on that and should be compatible with older
compilers that does not support __attribute__((symver))
yet.
Inspired by following code:
https://github.com/linux-rdma/rdma-core/blob/master/util/symver.h
