libftdi: C++ bindings need boost

According to libftdi configure.in:

"""
dnl libftdi C++ wrapper. Needs boost.
[...]
        if test "x$HAVE_BOOST" != "xyes"; then
            AC_MSG_ERROR(Sorry, we need the boost library for the C++ wrapper)
        fi
"""

And indeed, if you enable BR2_PACKAGE_LIBTFDI_CPP but don't have Boost
enabled, the libfdipp library is not built. To fix this, this commit
changes BR2_PACKAGE_LIBTFDI_CPP to select Boost.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libftdi/Config.in

@@ -12,11 +12,18 @@ config BR2_PACKAGE_LIBFTDI
 if BR2_PACKAGE_LIBFTDI
 
 config BR2_PACKAGE_LIBTFDI_CPP
-	depends on BR2_INSTALL_LIBSTDCPP
 	bool "C++ bindings"
+	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_PACKAGE_BOOST_ARCH_SUPPORTS
+	depends on BR2_USE_WCHAR
+	select BR2_PACKAGE_BOOST
 	help
 	  C++ bindings for libftdi
 
+comment "libftdi C++ bindings need a toolchain w/ wchar, C++"
+	depends on BR2_PACKAGE_BOOST_ARCH_SUPPORTS
+	depends on !BR2_USE_WCHAR || !BR2_INSTALL_LIBSTDCPP
+
 endif # BR2_PACKAGE_LIBFTDI
 
 comment "libftdi needs a toolchain w/ threads"

package/libftdi/libftdi.mk

@@ -15,6 +15,7 @@ LIBFDTI_CONF_OPTS = --without-examples
 
 # configure detect it automaticaly so we need to force it
 ifeq ($(BR2_PACKAGE_LIBTFDI_CPP),y)
+LIBFTDI_DEPENDENCIES += boost
 LIBFDTI_CONF_OPTS += --enable-libftdipp
 else
 LIBFDTI_CONF_OPTS += --disable-libftdipp