package/libargon2: add missing Config.in for the !BR2_STATIC_LIBS dependency

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libargon2/Config.in

@@ -6,3 +6,7 @@ config BR2_PACKAGE_LIBARGON2
 	  A modern password hashing algorithm
 
 	  https://password-hashing.net/#argon2
+
+comment "libargon needs a toolchain w/ dynamic library"
+	depends on BR2_USE_MMU
+	depends on BR2_STATIC_LIBS