Fix compilation against a karchive that doesn't have lzma

Fixes one of the problems with building for Android.
Note LZMA is an optional dependency for KArchive.

generators/comicbook/CMakeLists.txt

@@ -5,7 +5,6 @@ include_directories(
    ${CMAKE_CURRENT_SOURCE_DIR}/../..
 )
 
-
 ########### next target ###############
 
 set( okularGenerator_comicbook_PART_SRCS
@@ -25,6 +24,10 @@ if (UNIX AND NOT ANDROID)
    target_link_libraries(okularGenerator_comicbook KF5::Pty)
 endif ()
 
+if (KArchive_HAVE_LZMA)
+    target_compile_definitions(okularGenerator_comicbook PRIVATE -DWITH_K7ZIP=1)
+endif()
+
 ########### install files ###############
 install( FILES okularComicbook.desktop  DESTINATION  ${KDE_INSTALL_KSERVICES5DIR} )
 install( PROGRAMS okularApplication_comicbook.desktop org.kde.mobile.okular_comicbook.desktop  DESTINATION  ${KDE_INSTALL_APPDIR} )

generators/comicbook/document.cpp

@@ -18,7 +18,9 @@
 #include <QMimeDatabase>
 #include <kzip.h>
 #include <ktar.h>
+#if WITH_K7ZIP
 #include <k7zip.h>
+#endif
 
 #include <memory>
 
@@ -79,6 +81,7 @@ bool Document::open( const QString &fileName )
         if ( !processArchive() ) {
             return false;
         }
+#ifdef WITH_K7ZIP
     /**
      * We have a 7z archive
      */
@@ -88,6 +91,7 @@ bool Document::open( const QString &fileName )
         if ( !processArchive() ) {
             return false;
         }
+#endif
     } else if ( mime.inherits( QStringLiteral("application/x-cbr") ) || mime.inherits( QStringLiteral("application/x-rar") ) || mime.inherits( QStringLiteral("application/vnd.rar") ) ) {
         if ( !Unrar::isAvailable() ) {
             mLastErrorString = i18n( "Cannot open document, neither unrar nor unarchiver were found." );