This replaces the previous sed hackery with a proper patch, and removes
a few more libc functions that meslibc is missing.
The binary name is changed to "byacc" so it doesn't get overwritten by
heirloom yacc.
The bsearch() replacement code comes from an earlier version of byacc.
This is meant to replace heirloom yacc for compiling pre-musl parsers.
Unlike heirloom yacc, it's in the public domain, and can be linked with
meslibc without licensing concerns.
Gábor Stefanik