shared: Introduce new top-level dir and move 1st party lib code there.

This commit moves all first-party code developed for this project from lib/
to shared/, so that lib/ now only contains third-party code.

The following directories are moved as-is from lib to shared:

    lib/libc            -> shared/libc
    lib/memzip          -> shared/memzip
    lib/netutils        -> shared/netutils
    lib/timeutils       -> shared/timeutils
    lib/upytesthelper   -> shared/upytesthelper

All files in lib/embed/ have been moved to shared/libc/.

lib/mp-readline has been moved to shared/readline.

lib/utils has been moved to shared/runtime, with the exception of
lib/utils/printf.c which has been moved to shared/libc/printf.c.

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/shared/libc/__errno.c b/shared/libc/__errno.c
new file mode 100644
index 000000000..86417a02d
--- /dev/null
+++ b/shared/libc/__errno.c
@@ -0,0 +1,13 @@
+// This file provides a version of __errno() for embedded systems that do not have one.
+// This function is needed for expressions of the form: &errno
+
+static int embed_errno;
+
+#if defined(__linux__)
+int *__errno_location(void)
+#else
+int *__errno(void)
+#endif
+{
+    return &embed_errno;
+}