lib: c: re-organise into separate static modules, plus a single shared library

lib/libc/core/errno/errno.c

@@ -0,0 +1,54 @@
+#include <errno.h>
+#include <mango/status.h>
+
+#if defined(BUILD_STATIC)
+int __set_errno(int err)
+{
+	return -err;
+}
+#endif
+
+#if defined(BUILD_SHARED)
+int __set_errno(int err)
+{
+	/* TODO */
+	return -1;
+}
+#endif
+
+int __errno_from_kern_status(unsigned int err)
+{
+	switch (err) {
+	case KERN_OK:
+		return SUCCESS;
+	case KERN_UNIMPLEMENTED:
+		return ENOSYS;
+	case KERN_NAME_EXISTS:
+		return EEXIST;
+	case KERN_INVALID_ARGUMENT:
+		return EINVAL;
+	case KERN_UNSUPPORTED:
+		return ENOTSUP;
+	case KERN_NO_MEMORY:
+		return ENOMEM;
+	case KERN_NO_ENTRY:
+		return ENOENT;
+	case KERN_WOULD_BLOCK:
+		return EWOULDBLOCK;
+	case KERN_NO_DEVICE:
+		return ENODEV;
+	case KERN_DEVICE_STUCK:
+	case KERN_IO_ERROR:
+		return EIO;
+	case KERN_FATAL_ERROR:
+		return ENXIO;
+	case KERN_BAD_STATE:
+		return EPERM;
+	case KERN_MEMORY_FAULT:
+		return EFAULT;
+	case KERN_ACCESS_DENIED:
+		return EACCES;
+	default:
+		return EINVAL;
+	}
+}