And turn "" includes into full-path (which makes it easier to put
config.h first, and finds some cases check-includes.sh missed
previously).
config.h sets _GNU_SOURCE which really needs to be done before any
'#includes': we mainly got away with it with glibc, but other platforms
like Alpine may have stricter requirements.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I did this by copying the updated bech32 code, and then re-patching in
our minor changes:
1. Headers modded (we need size_t)
2. Explicit length for bech32_encode/decode (not 90).
3. Exposing and bech32_ prefix for convert_bits, charset, charset_rev.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
