libssh2: revert to previous crypto defaults

The recent crypto handling change (commit 04a1031d3: package/libssh2: Add
selectable crypto libraries) had the unfortunate side effect that it no
longer automatically selects the most suitable crypto backend (E.G.  one
where the dependency is already enabled), so all users not wanting to use
the mbedtls backend need to explicitly configure this.

Fix this by inverting the logic so the crypto backend sub options use
'depends on' their dependencies instead of 'select', so only the available
backends are displayed.

Like before, default to openssl if no crypto backend dependencies are
currently enabled.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libssh2/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_LIBSSH2
 	bool "libssh2"
+	select BR2_PACKAGE_OPENSSL if !(BR2_PACKAGE_MBEDTLS || BR2_PACKAGE_LIBGCRYPT)
 	help
 	  libssh2 is a client-side C library implementing the SSH2
 	  protocol as defined by Internet Drafts: SECSH-TRANS(22),
@@ -17,16 +18,15 @@ choice
 
 config BR2_PACKAGE_LIBSSH2_MBEDTLS
 	bool "mbedtls"
-	select BR2_PACKAGE_MBEDTLS
+	depends on BR2_PACKAGE_MBEDTLS
 
 config BR2_PACKAGE_LIBSSH2_LIBGCRYPT
 	bool "gcrypt"
-	depends on BR2_PACKAGE_LIBGPG_ERROR_ARCH_SUPPORTS # libgcrypt -> libgpg-error
-	select BR2_PACKAGE_LIBGCRYPT
+	depends on BR2_PACKAGE_LIBGCRYPT
 
 config BR2_PACKAGE_LIBSSH2_OPENSSL
 	bool "openssl"
-	select BR2_PACKAGE_OPENSSL
+	depends on BR2_PACKAGE_OPENSSL
 
 endchoice
 endif