Declare HAVE_ERROR_H only if error symbol is available
Musl doesn't provide error.h. But there exists a standalone implementation
that installs /usr/include/error.h but requires explicit linkage. This
leads linkage errors later on due to the assumption that error
symbols are provided by the libc.
Bug: https://bugs.gentoo.org/948878
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32548 Signed-off-by: Alfred Wingate <parona@protonmail.com>