Find libqrencode using cmake/pkg-config logic

cmake/FindQrencode.cmake

@@ -0,0 +1,11 @@
+include(PkgConfigWithFallback)
+find_pkg_config_with_fallback(Qrencode
+    PKG_CONFIG_NAME libqrencode
+    LIB_NAMES qrencode
+    INCLUDE_NAMES qrencode.h
+)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Qrencode
+    REQUIRED_VARS Qrencode_LIBRARY
+    VERSION_VAR Qrencode_VERSION)

plugins/omemo/CMakeLists.txt

@@ -10,6 +10,7 @@ find_packages(OMEMO_PACKAGES REQUIRED
     GObject
     GTK3
     Soup
+    Qrencode
 )
 
 set(RESOURCE_LIST
@@ -57,17 +58,18 @@ CUSTOM_VAPIS
     ${CMAKE_BINARY_DIR}/exports/xmpp-vala.vapi
     ${CMAKE_BINARY_DIR}/exports/qlite.vapi
     ${CMAKE_BINARY_DIR}/exports/dino.vapi
-    ${CMAKE_CURRENT_SOURCE_DIR}/vapi/qrencode.vapi
 PACKAGES
     ${OMEMO_PACKAGES}
 GRESOURCES
     ${OMEMO_GRESOURCES_XML}
+OPTIONS
+    --vapidir=${CMAKE_CURRENT_SOURCE_DIR}/vapi
 )
 
 add_definitions(${VALA_CFLAGS} -DGETTEXT_PACKAGE=\"${GETTEXT_PACKAGE}\" -DLOCALE_INSTALL_DIR=\"${LOCALE_INSTALL_DIR}\")
 add_library(omemo SHARED ${OMEMO_VALA_C} ${OMEMO_GRESOURCES_TARGET})
 add_dependencies(omemo ${GETTEXT_PACKAGE}-translations)
-target_link_libraries(omemo libdino signal-protocol-vala qrencode ${OMEMO_PACKAGES})
+target_link_libraries(omemo libdino signal-protocol-vala ${OMEMO_PACKAGES})
 set_target_properties(omemo PROPERTIES PREFIX "")
 set_target_properties(omemo PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/plugins/)