package/unixodbc: add optional dependency to libtool

To get reproducible builds of unixodbc add libtool as optional
dependency.

Without libtool:

$ host/usr/bin/x86_64-linux-readelf -a target/usr/lib/libodbc.so.2.0.0 | grep NEEDED
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.0]

With libtool:

$ host/usr/bin/x86_64-linux-readelf -a target/usr/lib/libodbc.so.2.0.0 | grep NEEDED
 0x0000000000000001 (NEEDED)             Shared library: [libltdl.so.7]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.0]

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/unixodbc/unixodbc.mk

@@ -20,6 +20,13 @@ else
 UNIXODBC_CONF_OPTS += --disable-iconv
 endif
 
+ifeq ($(BR2_PACKAGE_LIBTOOL),y)
+UNIXODBC_CONF_OPTS += --without-included-ltdl
+UNIXODBC_DEPENDENCIES += libtool
+else
+UNIXODBC_CONF_OPTS += --with-included-ltdl
+endif
+
 ifeq ($(BR2_PACKAGE_READLINE),y)
 UNIXODBC_CONF_OPTS += --enable-readline
 UNIXODBC_DEPENDENCIES += readline