Recognizing addresses from those networks allows us to accept and gossip
them, even though we don't know how to connect to them (yet).
Co-authored-by: eriknylund <erik@daychanged.com>
The way we currently test with AC_CHECK_DECLS do not work with Clang:
```bash
configure:21492: clang++-10 -std=c++11 -c -g -O2 -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS conftest.cpp >&5
conftest.cpp💯10: error: builtin functions must be directly called
(void) __builtin_clz;
^
1 error generated.
```
This also removes the __builtin_clz() check, as we don't actually use
it anywhere, and it's trvial to re-add detection if we do start using
it at some point.
All the other files in the repo which include bitcoin-config.h do so with the appropriate subfolder prefixed: config/bitcoin-config.h
The header should be included with the appropriate subfolder here as well.
This canonicalization also allows getting rid of a bit of extra configuration in Makefile.am.
- Detect endian instead of stopping configure on big-endian
- Add `byteswap.h` and `endian.h` header for compatibility with
Windows and other operating systems that don't come with them
- Update `crypto/common.h` functions to use compat
endian header
