Add a "fork" of musl as //fusl.

fusl/src/conf/fpathconf.c

+#include <unistd.h>
+#include <limits.h>
+#include <errno.h>
+
+long fpathconf(int fd, int name)
+{
+        static const short values[] = {
+                [_PC_LINK_MAX] = _POSIX_LINK_MAX,
+                [_PC_MAX_CANON] = _POSIX_MAX_CANON,
+                [_PC_MAX_INPUT] = _POSIX_MAX_INPUT,
+                [_PC_NAME_MAX] = NAME_MAX,
+                [_PC_PATH_MAX] = PATH_MAX,
+                [_PC_PIPE_BUF] = PIPE_BUF,
+                [_PC_CHOWN_RESTRICTED] = 1,
+                [_PC_NO_TRUNC] = 1,
+                [_PC_VDISABLE] = 0,
+                [_PC_SYNC_IO] = 1,
+                [_PC_ASYNC_IO] = -1,
+                [_PC_PRIO_IO] = -1,
+                [_PC_SOCK_MAXBUF] = -1,
+                [_PC_FILESIZEBITS] = FILESIZEBITS,
+                [_PC_REC_INCR_XFER_SIZE] = 4096,
+                [_PC_REC_MAX_XFER_SIZE] = 4096,
+                [_PC_REC_MIN_XFER_SIZE] = 4096,
+                [_PC_REC_XFER_ALIGN] = 4096,
+                [_PC_ALLOC_SIZE_MIN] = 4096,
+                [_PC_SYMLINK_MAX] = SYMLINK_MAX,
+                [_PC_2_SYMLINKS] = 1
+        };
+        if (name >= sizeof(values)/sizeof(values[0])) {
+                errno = EINVAL;
+                return -1;
+        }
+        return values[name];
+}