package/leptonica: add libwebp{demux, mux} optional dependency

leptonica optionally depends on webp/demux.h and webp/mux.h since
version 1.79.0:
https://github.com/DanBloomberg/leptonica/commit/a7c5bcdf04062aad3655642bdb853561a1c49733
https://github.com/DanBloomberg/leptonica/commit/0ce4b9cc0845b198583d51f0a0df277de8f8c5fa

Fixes:
 - http://autobuild.buildroot.org/results/1f8531e1651e82a1e93707ccb205d0e7a3cae1a3

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/leptonica/leptonica.mk

@@ -51,8 +51,15 @@ endif
 ifeq ($(BR2_PACKAGE_WEBP),y)
 LEPTONICA_DEPENDENCIES += webp
 LEPTONICA_CONF_OPTS += --with-libwebp
+ifeq ($(BR2_PACKAGE_WEBP_DEMUX)$(BR2_PACKAGE_WEBP_MUX),yy)
+LEPTONICA_CONF_OPTS += --with-libwebpmux
 else
-LEPTONICA_CONF_OPTS += --without-libwebp
+LEPTONICA_CONF_OPTS += --without-libwebpmux
+endif
+else
+LEPTONICA_CONF_OPTS += \
+	--without-libwebp \
+	--without-libwebpmux
 endif
 
 ifeq ($(BR2_PACKAGE_ZLIB),y)